Answer
(a) $x=12$
(b) Use an interval beyond $[-10,10]$ to include 12.
Work Step by Step
(a)
We solve:
$-2(x-5)=-x-2$
$-2x+10=-x-2$
$10=x-2$
$x=10+2$
$x=12$
(b) Most standard viewing windows span the interval $[-10,10]$, outside of the solution. We must use an interval around $12$, e.g. $[8,15]$.