Answer
$A=50$, $B=125$, $C=5$ and $x=40$.
Work Step by Step
Since the triangles are similar, then the angles are equal. That is
$A=50$, $B=125$, $C=5$.
To find $x$, we set up a ratio between corresponding sides:
$$
\frac{x}{50}=\frac{8}{10}=\frac{4}{5}\Longrightarrow x=\frac{4\times50}{5}=40
. $$
