#### Answer

$\color{blue}{\left\{4, 8\right\}}$

#### Work Step by Step

RECALL:
Zero-Factor Property:
If $ab = 0$, then either $a=0$ or $b=0$ or both are $0$.
Use the property above to obtain:
\begin{array}{ccc}
&x-8=0 &\text{or} &x-4=0
\end{array}
Solve each equation to obtain:
$x=8$ or $x=4$
Thus, the solution set is $\color{blue}{\left\{4, 8\right\}}$.