Answer
$r=18$
Work Step by Step
$\begin{align*}
r+(-8)+8&=10+8 &\text{Add 8 to each side of the equation.}\\
r&=18 &\text{Simplify}.
\end{align*}$
Check if the solution is correct by substituting $18$ to the variable in the original equation:
$\begin{align*}
r+(-8)&=10\\
18+(-8)&\stackrel{?}{=}10\\
10&\stackrel{\checkmark}{=}10
\end{align*}$
Thus, the solution is $r=18$.
