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## Substitution

### If the value for only one of the variables is given

Look over the problem below.

b = 3
5b - 2c + c / b

As you can see, the expression has two variables b and c, but in this problem, only the value for b is given. Don't panic! Simply substitute the variable b with the number 3, don't worry about doing anything with the variable c.

5(3) - 2c + c / (3)

Then simplify as much as you can using the Order of Operations:

### If the value for one of the variables is not a number

In this case, as in the problem below, you must substitute the variable with the expression given.

b = c + 1
5b - 2c + c / b

#### NOTE

This problem is one instance where it is absolutely necessary to enclose the expression or number that you are substituting a variable for in parentheses. Because of the Order of Operations 5(c + 1) is not the same as 5c + 1.

Substitute:

5(c + 1) - 2c + c / (c + 1)

Simplify:

5c + 5 - 2c + c / (c + 1)

Proceed to the next page for more substitution resources.

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