# ISEE Middle Level Math : How to subtract variables

## Example Questions

### Example Question #31 : How To Subtract Variables

Simplify the following:

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:

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 #820 : Concepts

Simplify:

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 #33 : How To Subtract Variables

Simplify:

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 #34 : How To Subtract Variables

Simplify the following:

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 #35 : How To Subtract Variables

Simplify the following statement:

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

### Example Question #36 : How To Subtract Variables

Subtract the following:

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 #37 : How To Subtract Variables

Subtract the following:

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 #38 : How To Subtract Variables

Solve the following:

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 #39 : How To Subtract Variables

Solve the following: