To isolate the variable, undo the addition and then the multiplication.

1
SOLUTION
To isolate the variable, undo the addition and
then the multiplication.
Write original equation.
Subtract 6 from each side.
Simplify.
Multiply each side by 3.
Simplify.
2
Solve 7x 3x 8 24.
7x 3x 8 24
Write original equation.
4x 8 24
Combine like terms.
Add 8 to each side.
4x 8 8 24 8
4x 32
Simplify.
Divide each side by 4.
Simplify.
3
Solve 5x 3(x 4) 28.
METHOD 1 Show All Steps
METHOD 2 Do Some Steps Mentally
5x 3(x 4) 28
5x 3(x 4) 28
5x 3x 12 28
5x 3x 12 28
8x 12 28
8x 12 28
8x 12 12 28 12
8x 16
8x 16
4
Multiplying by a Reciprocal First
Solving equations systematically is an
example of deductive reasoning. Notice how each
solution step is based on number properties or
properties of equality.
Write original equation.
55 x 3
Simplify.
Subtract 3 from each side.
5
SOLVING REAL-LIFE PROBLEMS
A body temperature of 95 F or lower may indicate
the medical condition called hypothermia. What
temperature on the Celsius scale may indicate
hypothermia?
Write known formula.
Substitute 95 for F.
Subtract 32 from each side.
35 C