Answer
$x=40
\\A=50^o
\\B=125^o
\\C=5^o$
Work Step by Step
RECALL:
Two similar triangles have:
(1) corresponding angles that are congruent; and
(2) corresponding sides that are proportional
Since corresponding angles are congruent, then
$A=50^o
\\B=125^o
\\C=5^o$
Corresponding sides of similar triangles are proportional.
Thus,
$\dfrac{10}{8}=\dfrac{50}{x}$
Cross-multiply to obtain:
$\begin{array}{ccc}
&10(x) &= &50(8)
\\&10x &= &400
\\&\frac{10x}{10} &= &\frac{400}{10}
\\&x &= &40\end{array}$
