# If 4a+b=12, then what is a?

Dec 20, 2015

$a = \frac{12 - b}{4}$ or $3 - \frac{b}{4}$

#### Explanation:

$4 a + b = 12$

Subtract $b$ from both sides.

$4 a + b$ $\textcolor{red}{- b} = 12$ $\textcolor{red}{- b}$

$4 a = 12 - b$

Divide $4$ from both sides.

$4 a \textcolor{red}{\div 4} = \left(12 - b\right) \textcolor{red}{\div 4}$

$a = \frac{12 - b}{4}$ or $3 - \frac{b}{4}$