Creating/Solving One Variable Equations/Inequalities

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Algebra 2 › Creating/Solving One Variable Equations/Inequalities

Questions 1 - 10
1

A ball is thrown upward from a platform. Its height (in feet) after $t$ seconds is modeled by $h(t)=-16t^2+48t+64$. Write and solve an equation to find when the ball hits the ground.

Let $t$ = time in seconds (use the solution that makes sense in context).​

Set $-16t^2+48t+64=0$. Solution: $t=2$. The ball hits the ground at $t=2$ seconds.

Set $-16t^2+48t+64=0$. Solutions: $t=4$ and $t=-1$. The ball hits the ground at $t=4$ seconds.

Set $-16t^2+48t+64=0$. Solutions: $t=4$ and $t=1$. The ball hits the ground at $t=1$ second.

Set $-16t^2+48t+64=0$. Solutions: $t=1$ and $t=-4$. The ball hits the ground at $t=1$ second.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Projectile motion problems lead to quadratic equations: the height function h(t) = -16t² + v₀t + h₀ represents vertical motion under gravity, where -16 is half the acceleration due to gravity (in ft/s²), v₀ is initial velocity, and h₀ is initial height. The ball hits the ground when h(t) = 0. Setting -16t² + 48t + 64 = 0 and dividing by -16: t² - 3t - 4 = 0. Factoring: (t-4)(t+1) = 0, giving t = 4 or t = -1. Since time cannot be negative in this context, t = 4 seconds. We can verify: h(4) = -16(16) + 48(4) + 64 = -256 + 192 + 64 = 0 ✓. Choice A correctly sets the height equation equal to zero (-16t² + 48t + 64 = 0) and solves to get t = 4 and t = -1, properly rejecting the negative time to conclude the ball hits the ground at t = 4 seconds. Choice B incorrectly states the solutions are t = 1 and t = -4, but substituting t = 1 gives h(1) = -16 + 48 + 64 = 96 feet, not 0. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

2

One printer can print a batch of flyers in 10 minutes. A second printer can print the same batch in 15 minutes. If both printers run together, how long will it take to print one batch?

Write and solve an equation to find the time.

Let $t$ = time in minutes to print one batch together.

Set up $\frac{1}{10}-\frac{1}{15}=\frac{1}{t}$. Then $t=30$ minutes. Together they print a batch in 30 minutes.

Set up $\frac{1}{10}+\frac{1}{15}=t$. Then $t=\frac{1}{6}$ minute. Together they print a batch in $\frac{1}{6}$ minute.

Set up $\frac{1}{10}+\frac{1}{15}=\frac{1}{t}$. Then $t=6$ minutes. Together they print a batch in 6 minutes.

Set up $10+15=t$. Then $t=25$ minutes. Together they print a batch in 25 minutes.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Work-rate problems lead to rational equations: if one worker completes a job in time t₁ and another in t₂, their combined rate is 1/t₁ + 1/t₂ (adding rates), which equals 1/t_combined. The reciprocals represent 'fraction of job per hour,' and adding these fractions gives the combined rate. Solving these rational equations requires finding LCD and often produces fractional time answers that make sense: 3.4 hours = 3 hours 24 minutes. For these printers, set up 1/10 + 1/15 = 1/t; common denominator 30 gives (3 + 2)/30 = 5/30 = 1/6, so t = 6 minutes to print the batch together. Choice A correctly sets up by adding rates and solves to find t=6 minutes. Choice B adds the rates but forgets the reciprocal, resulting in a tiny time that implies impossibly fast printing. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

3

A tank is being filled by two hoses. Hose A can fill the tank in 6 hours and Hose B can fill the same tank in 9 hours.

Write and solve an equation to find how long it takes to fill the tank if both hoses run together.

Let $t$ = the number of hours to fill the tank together.

Set up $6+9=t$. Then $t=15$ hours. The tank fills in 15 hours.

Set up $\frac{1}{6}+\frac{1}{9}=\frac{1}{t}$. Then $t=\frac{18}{5}$ hours. The tank fills in $3.6$ hours.

Set up $\frac{1}{6}+\frac{1}{9}=t$. Then $t=\frac{5}{18}$ hours. The tank fills in about $0.28$ hours.

Set up $\frac{1}{6}-\frac{1}{9}=\frac{1}{t}$. Then $t=18$ hours. The tank fills in 18 hours.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Work-rate problems lead to rational equations: if one worker completes a job in time t₁ and another in t₂, their combined rate is 1/t₁ + 1/t₂ (adding rates), which equals 1/t_combined. The reciprocals represent 'fraction of job per hour,' and adding these fractions gives the combined rate. Solving these rational equations requires finding LCD and often produces fractional time answers that make sense: 3.4 hours = 3 hours 24 minutes. For this tank-filling scenario, set up the equation as 1/6 + 1/9 = 1/t; finding a common denominator of 18 gives (3 + 2)/18 = 5/18, so 1/t = 5/18 and t = 18/5 = 3.6 hours, meaning together they fill the tank in 3 hours and 36 minutes. Choice A correctly sets up the equation by adding the rates and solves to find t = 18/5 hours, which is the accurate combined time. A common distractor like choice B forgets to take the reciprocal after adding the rates, leading to an unrealistically small time that doesn't make sense for combined effort. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

4

A streaming channel has 2,500 subscribers and grows by 12% each month.

Model the situation with an exponential equation and solve for the number of months $t$ until the channel reaches 5,000 subscribers.

Let $t$ = number of months.

Set up $2500(1.12)^t=5000$. Then $t=\log_{1.12}(0.5)\approx -6.12$. About 6.1 months.

Set up $2500(0.88)^t=5000$. Then $t=\log_{0.88}(2)\approx -5.42$. About 5.4 months.

Set up $2500+1.12t=5000$. Then $t\approx 2232.14$. About 2232 months.

Set up $2500(1.12)^t=5000$. Then $t=\log_{1.12}(2)\approx 6.12$. About 6.1 months.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Exponential growth/decay problems arise when something grows or shrinks by a constant percent: 'grows 8% yearly' means multiply by 1.08 each year, giving formula amount = initial × $(1.08)^t$. To find when it reaches a specific value, set up equation like $500(1.08)^t$ = 1000 and solve using logarithms: $(1.08)^t$ = 2, so t = ln(2)/ln(1.08) ≈ 9 years. The logarithm unlocks the exponent! For this subscriber growth, $2500(1.12)^t$ = 5000; dividing by 2500 gives $(1.12)^t$ = 2, t = ln(2)/ln(1.12) ≈ 6.12 months to reach 5000 subscribers. Choice A correctly sets up the exponential equation and solves using logs for about 6.1 months. Choice D uses linear addition instead of exponential multiplication, leading to an impractically long time. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

5

A gym charges a one-time signup fee of $\$60$ plus $$18$ per month. You have at most $\$240$ to spend.

Create an inequality for this constraint and find the maximum number of whole months you can afford.

Let $m$ = number of months.

Set up $60m+18\le 240$. Then $m\le 3.7$. Maximum is 3 months.

Set up $60+18m\ge 240$. Then $m\ge 10$. Maximum is 10 months.

Set up $18m-60\le 240$. Then $m\le 16.67$. Maximum is 16 months.

Set up $60+18m\le 240$. Then $m\le 10$. Maximum is 10 months.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Budget constraints often lead to linear inequalities: total cost = fixed + variable × quantity ≤ limit, solved by isolating the variable and considering whole numbers if needed. For this gym fee, set up 60 + 18m ≤ 240; subtracting 60 gives 18m ≤ 180, so m ≤ 10, meaning the maximum whole months is 10. Choice A correctly sets up the inequality with the signup fee and monthly cost, solving to find the maximum of 10 months. A distractor like choice B reverses the inequality direction, which would incorrectly suggest a minimum instead of a maximum. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

6

A number has the property that the sum of the number and its reciprocal is $\frac{10}{3}$.

What equation represents this context? Solve it and interpret the solution(s).

Let $x$ = the number, with $x\ne 0$.

Set up $\frac{x+1}{x}=\frac{10}{3}$. Solving gives $x=\frac{3}{7}$. The number is $\frac{3}{7}$.

Set up $x-\frac{1}{x}=\frac{10}{3}$. Solving gives $x=3$ or $x=\frac{1}{3}$. Both satisfy the condition.

Set up $x+\frac{1}{x}=\frac{10}{3}$. Solving gives $x=3$ or $x=\frac{1}{3}$. Both satisfy the condition.

Set up $x+\frac{1}{x}=\frac{10}{3}$. Solving gives $x=\frac{10}{3}$. The number is $\frac{10}{3}$.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Problems involving a number and its reciprocal often lead to rational equations that simplify to quadratics: multiply through by x to clear the denominator. For this, set up x + 1/x = 10/3; multiplying by x gives x² + 1 = (10/3)x, then x² - (10/3)x + 1 = 0; multiplying by 3 yields 3x² - 10x + 3 = 0, solutions x = [10 ± √(100 - 36)]/6 = [10 ± 8]/6, so x=3 or x=1/3, both valid as they sum to 10/3 with their reciprocals. Choice A correctly sets up the sum equation and solves to find both valid solutions. Choice B incorrectly assumes the solution is directly 10/3 without solving the quadratic, missing the actual values. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

7

A rectangular patio has an area of 96 square meters. Its length is 4 meters more than its width.

Write and solve an equation to find the width and length.

Let $w$ = the width in meters.

Set up $w^2+4=96$. Then $w=\sqrt{92}$. Width $\sqrt{92}$ m and length $\sqrt{92}+4$ m.

Set up $w+w+4=96$. Then $w=46$. Width 46 m and length 50 m.

Set up $w(w+4)=96$. Then $w=8$ (reject $w=-12$). Width 8 m and length 12 m.

Set up $w(w-4)=96$. Then $w=12$ (reject $w=-8$). Width 12 m and length 8 m.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Area problems with relationships between dimensions often lead to quadratic equations: if length is width plus a constant, area = width × (width + constant), forming a quadratic like w(w + 4) = 96 that you solve using factoring or quadratic formula, rejecting negative roots. Here, the equation is w(w + 4) = 96, expanding to w² + 4w - 96 = 0; solving gives w = [-4 ± √(16 + 384)]/2 = [-4 ± √400]/2 = [-4 ± 20]/2, so w = 8 or w = -12 (rejected), with length 12 m. Choice A correctly sets up the quadratic from area and solves to find width 8 m and length 12 m. A distractor like choice B confuses area with perimeter, leading to incorrect large dimensions that don't match the given area. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

8

A rectangular patio has an area of $96\text{ m}^2$. Its length is 4 meters more than its width.

Set up a quadratic equation and solve to find the patio’s width and length.

Let $w$ = the width in meters.​

Set up $w(w+4)=96$. Then $w^2+4w-96=0$, so $w=12$ (reject $-8$). The patio is $12\text{ m}$ by $16\text{ m}$.

Set up $w+(w+4)=96$. Then $2w+4=96$, so $w=46$. The patio is $46\text{ m}$ by $50\text{ m}$.

Set up $w(w+4)=96$. Then $w^2+4w-96=0$, so $w=8$ (reject $-12$). The patio is $8\text{ m}$ by $12\text{ m}$.

Set up $w(w-4)=96$. Then $w^2-4w-96=0$, so $w=12$ (reject $-8$). The patio is $12\text{ m}$ by $8\text{ m}$.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Area problems with related dimensions often lead to quadratic equations: if length is width plus a constant, set up area = width × (width + constant), resulting in w² + cw - area = 0, solved via factoring or quadratic formula, rejecting negative roots since dimensions are positive. For this patio, set up w(w + 4) = 96, expand to w² + 4w - 96 = 0, use quadratic formula w = [-4 ± √(16 + 384)]/2 = [-4 ± √400]/2 = [-4 ± 20]/2, so w = 8 or w = -12 (reject negative), meaning width 8 m and length 12 m. Choice A correctly sets up the quadratic with length as w + 4 and solves to find the dimensions 8 m by 12 m. A distractor like choice C mistakenly uses a linear equation by adding sides instead of multiplying for area, resulting in impossible dimensions. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

9

A community pool has two pumps that can fill it. Pump A can fill the pool in 6 hours, and Pump B can fill the pool in 8 hours.

Write and solve a rational equation to find how long it takes to fill the pool if both pumps run at the same time.

Let $t$ = the time (in hours) to fill the pool together.​

Set up $\frac{6}{t}+\frac{8}{t}=1$. Then $t=14$ hours, so it takes 14 hours together.

Set up $6+8=t$. Then $t=14$ hours, so it takes 14 hours together.

Set up $\frac{1}{6}+\frac{1}{8}=\frac{1}{t}$. Then $t=\frac{14}{3}$ hours, so it takes about 4.67 hours together.

Set up $\frac{1}{6}+\frac{1}{8}=\frac{1}{t}$. Then $t=\frac{24}{7}$ hours, so it takes about 3.43 hours together.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Work-rate problems lead to rational equations: if one worker completes a job in time t₁ and another in t₂, their combined rate is 1/t₁ + 1/t₂ (adding rates), which equals 1/t_combined. The reciprocals represent 'fraction of job per hour,' and adding these fractions gives the combined rate. Solving these rational equations requires finding LCD and often produces fractional time answers that make sense: 3.4 hours = 3 hours 24 minutes. For this pool-filling scenario, set up the equation as 1/6 + 1/8 = 1/t; find a common denominator of 24 to get 4/24 + 3/24 = 7/24 = 1/t, so t = 24/7 ≈ 3.43 hours, meaning both pumps together fill the pool in about 3 hours 26 minutes. Choice B correctly sets up the equation by adding the rates and solves to find t = 24/7 hours, accurately determining the combined time. A common mistake, as in choice C, is adding the individual times instead of the rates, which overestimates the combined time since they work together faster. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

10

A number and its reciprocal have a sum of $\frac{10}{3}$.

What equation represents this context? Solve it and interpret the solutions.

Let $x$ = the number (assume $x\ne 0$).​

Set up $x+\frac{1}{x}=\frac{10}{3}$. Then $3x^2-10x+3=0$, so $x=3$ or $x=\frac{1}{3}$.

Set up $x+\frac{1}{x}=\frac{10}{3}$. Then $3x^2-10x+3=0$, so $x=\frac{3}{10}$ only.

Set up $x-\frac{1}{x}=\frac{10}{3}$. Then $3x^2-10x-3=0$, so $x=3$ or $x=\frac{1}{3}$.

Set up $\frac{1}{x}=\frac{10}{3}x$. Then $x=\pm\sqrt{\frac{3}{10}}$, so the number is $\pm\sqrt{\frac{3}{10}}$.

Explanation

This question tests your ability to translate complex real-world situations into mathematical equations (linear, quadratic, rational, or exponential) and solve them to answer practical questions. Reciprocal relationships often lead to rational equations that become quadratic: for x + 1/x = k, multiply by x to get x² - kx + 1 = 0, solved via quadratic formula, with solutions being reciprocals if valid. For this number, set up x + 1/x = 10/3, multiply by 3x to clear fractions: 3x² + 3 = 10x, rearrange to 3x² - 10x + 3 = 0, factor as (3x - 1)(x - 3) = 0, so x = 3 or x = 1/3, meaning the numbers are 3 and its reciprocal 1/3. Choice A correctly sets up the sum equation and solves to find both solutions x = 3 and x = 1/3. A mistake like in choice C changes addition to subtraction, altering the relationship and solutions. Context-to-equation type matching: (1) Constant rates and simple relationships → linear, (2) Area, projectile motion, optimization → quadratic, (3) Combined work rates, mixture concentrations, reciprocal relationships → rational, (4) Percent growth/decay over time → exponential. The context language tells you which type: 'per unit' suggests linear, 'area' suggests quadratic, 'together complete' suggests rational (adding reciprocals), 'percent per year' suggests exponential. Identify the type, then use the appropriate solving method! The reality check is essential: after solving, ask: (1) Does the answer satisfy the original equation? (substitute back), (2) Does it make sense in the real world? (no negative quantities, no fractional discrete items), (3) Have I answered what was asked? (find time, not rate; find width, not area). For rational equations, check that denominators aren't zero. For exponential, verify the value is reasonable for the time scale. This three-part check catches most errors and ensures your math answer is also a real-world answer!

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