Answer
$\angle x\ and\ \angle z\ are\ 100^o$
$\angle y\ is\ 80^o$
Work Step by Step
When parallel lines are cut by a transversal, opposite interior angles are equal. $\angle y$ is equal to the $180^o$ angle.
$\angle x$ and the $80^o$ angle are supplementary.
$\angle x=180^o-80^o=100^o$
Corresponding angles are also equal. $\angle z=\angle x=100^o$
