Answer
$r=-8$
Work Step by Step
Use the Division Property of Equality by dividing $-8$ to both sides of the equation:
$$\begin{align*}
\frac{-8r}{-8}&=\frac{64}{-8}\\
r&=-8\end{align*}$$
Check the solution by substituting $-8$ to the variable in the given equation:
$$\begin{align*}
-8r&=64\\
-8(-8)&\stackrel{?}{=}64\\
64&\stackrel{\checkmark}{=}64\end{align*}$$
Thus, the solution is $r=-8$.
