ISEE Middle Level Math : How to subtract variables

Study concepts, example questions & explanations for ISEE Middle Level Math

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Example Questions

Example Question #31 : How To Subtract Variables

Simplify the following:

Possible Answers:

Correct answer:

Explanation:

To subtract variables, we will think of the variables as objects.  So, in the problem

let's think of the variable y as pens.  So, we can look at the problem as we currently have 9 pens.  We let our friends borrow 3 pens.  How many pens do we have now? The answer is 6.  We now have 6 pens.  

We can subtract the variables in the same way.  So,

Example Question #32 : How To Subtract Variables

Simplify the following:

Possible Answers:

Correct answer:

Explanation:

To subtract variables, we will look at the variables as objects.  So, 

we can look at it as the following.  We have 5 dollars.  We go to the store and buy something and spend 2 dollars.  How many dollars do we have now?  We now have 3 dollars.  We subtract variables in the same way. So

Example Question #101 : Variables

Simplify:

Possible Answers:

Correct answer:

Explanation:

When solving this problem we need to remember our order of operations, or PEMDAS. 

PEMDAS stands for parentheses, exponents, multiplication/division, and addition/subtraction. When you have a problem with several different operations, you need to solve the problem in this order and you work from left to right for multiplication/division and addition/subtraction.

Parentheses: We are not able to add a variable  to a number, so we move to the next step. 

Multiplication: We can distribute (or multiply) the 

Addition/Subtraction: Remember, we can't add a variable  to a number, so the  is left alone.

Example Question #101 : Variables

Simplify:

Possible Answers:

Correct answer:

Explanation:

When solving this problem we need to remember our order of operations, or PEMDAS. 

PEMDAS stands for parentheses, exponents, multiplication/division, and addition/subtraction. When you have a problem with several different operations, you need to solve the problem in this order and you work from left to right for multiplication/division and addition/subtraction.

Parentheses: We are not able to add a variable  to a number, so we move on to the next step

Multiplication: We can distribute the negative sign to the  and 

Remember, a negative times a negative will equal a positive, so we have a 

Finally we can combine like terms

Example Question #33 : How To Subtract Variables

Simplify the following:

Possible Answers:

Correct answer:

Explanation:

To subtract variables, we will think of the variables as objects.  So, given

we can think of x as grapes.  So, we start with 10 grapes.  If we eat 2 grapes, how many grapes do we have now?  We have 8 grapes.  We can subtract variables the same way.

Example Question #34 : How To Subtract Variables

Simplify the following statement:

Possible Answers:

Correct answer:

Explanation:

Simplify the following statement:

We have two terms, each with the same exponent. We can complete this problem by subtracting the coefficients just as we would do any other subtraction

So our answer is just

Example Question #35 : How To Subtract Variables

Subtract the following:

Possible Answers:

Correct answer:

Explanation:

To subtract variables, we will look at the variables like objects.  So in the problem

we will think of b as being balloons.  So we can read this problem as

So, if we have 8 balloons, and we give away 2 balloon, how many balloons do we have now?

 

We subtract variables the same way.  So,

We can look at this as we have 8 of something, if we subtract 2 of those somethings, how many do we have now?

Example Question #36 : How To Subtract Variables

Subtract the following:

Possible Answers:

Correct answer:

Explanation:

When subtracting variables, we can look at the variables as objects, then subtract those objects.

We can think of the variable b as bananas. So, we can look at it as

We can think of it like this:  If we buy 9 bananas at the store, and we eat 2 bananas, how many bananas do we have now?  We have 7 bananas left. So,

 

We subtract variables the same way.

Example Question #141 : Operations

Solve the following:

Possible Answers:

Correct answer:

Explanation:

When subtracting variables, we can think of the variables as objects.  So, in the problem

we can think of the variable c as cookies.  So, we can write it like

We can think of it like this:  There are 12 cookies on a plate.  We eat 2 of the cookies.  How many cookies are left?  There are 10 cookies left on the plate.

So, we get

 

We subtract variables the same way:

Example Question #142 : Operations

Solve the following:

Possible Answers:

Correct answer:

Explanation:

To subtract variables, we will think of the variables as objects. So, in the problem

we can think of the variable b as bottles of water.  So, we can write it like

We can think of it like this:  A cooler has 10 bottles of water.  You take 1 bottle of water from the cooler.  How many bottles of water are left in the cooler?  There are 9 bottles of water in the cooler.  So,

 

We subtract variables the same way:

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