Pre-Algebra Demystified

SOLUTION

x
 8 ¼ 22

x
 8 þ 8 ¼ 22 þ8 Add 8 to both sides

x
 0 ¼ 30

x¼ 30

Check:

x
 8 ¼ 22

30 
 8 ¼ 22

22 ¼ 22

An equation such as xþ 5 ¼9 can be solved by thesubtraction principle.

The same number can be subtracted from both members of the equation

without changing the nature of the equation.

EXAMPLE

Solve xþ 5 ¼9.

SOLUTION

xþ 5 ¼ 9

xþ 5 
 5 ¼ 9 
5 Subtract 5 from both sides

xþ 0 ¼ 4

x¼ 4

Check:

xþ 5 ¼ 9

4 þ 5 ¼ 9

9 ¼ 9

An equation such as 7x¼28 can be solved by using thedivision principle.

Both sides of an equation can be divided by the same non-zero number without

changing the nature of the equation.

EXAMPLE

Solve 7x¼28.

136 CHAPTER 7 Expression and Equations