# If f(x) = 3x - 4, how do you solve f(x) = 5?

Oct 20, 2015

$x = 3$

#### Explanation:

If
$\textcolor{w h i t e}{\text{XXX}} f \left(x\right) = 3 x - 4$
and
$\textcolor{w h i t e}{\text{XXX}} f \left(x\right) = 5$
then
$\textcolor{w h i t e}{\text{XXX}} 3 x - 4 = 5$

Add $4$ to both sides:
$\textcolor{w h i t e}{\text{XXX}} 3 x = 9$

Divide both sides by $3$
$\textcolor{w h i t e}{\text{XXX}} x = 3$