Question

find the measure of the missing angles.

Explanation:

Step1: Use angle - sum property for right - angle

Since the angle with measure $51^{\circ}$ and $x$ form a right - angle (90°), we can find $x$ by subtracting 51° from 90°.
$x = 90^{\circ}-51^{\circ}$

Step2: Use angle - sum property for straight - angle

The angle $y$ and the right - angle (90°) form a straight - angle (180°). So we can find $y$ by subtracting 90° from 180°.
$y=180^{\circ} - 90^{\circ}$

Answer:

$x = 39^{\circ}$, $y = 90^{\circ}$