## Basic College Mathematics (9th Edition)

$a=-3$
We are given the equation $-15=3(a-2)$. In order to solve, we can use the distributive property to simplify on the right side. $-15=3(a-2)=3(a)+3(-2)=3a-6$ Add 6 to both sides. $-15+6=3a-6+6$ $-9=3a$ Divide both sides by 3. $\frac{-9}{3}=\frac{3a}{3}$ Therefore, $a=-3$.