jmc

Knowing that $3$ is a root of $9$, we see that $x=8,2$. Hence, the sum of the roots is $10$.

Alternatively, we can rearrange the equation so that we have $x^2-10x+16=0$. Then, using the case of Vieta's formula for a quadratic, we again see that the sum of the roots is $\boxed{10}$.