Pre-Algebra Demystified

SOLUTION

2xþ 5 þ3x¼ 30

5xþ 5 ¼ 30 Combine 2xþ3x

5xþ 5 
 5 ¼ 30 
5 Subtract 5

5x¼ 25

5 x

5

¼

25

5

Divide by 5

x¼ 5

Check:

2xþ 5 þ3x¼ 30

2 ð 5 Þþ 5 þ 3 ð 5 Þ¼ 30

10 þ 5 þ 15 ¼ 30

15 þ 15 ¼ 30

30 ¼ 30

If an equation has parentheses, use the distributive property to remove
parentheses.

EXAMPLE

Solve 3(2xþ6)¼30.

SOLUTION

3 ð2xþ 6 Þ¼ 30

6xþ 18 ¼ 30 Remove parentheses

6xþ 18 
 18 ¼ 30 
 18 Subtract 18

6x¼ 12

6 x

6

¼

12

6

Divide by 6

x¼ 2

CHAPTER 7 Expression and Equations 141