9514 1404 393
Answer:
132°
Explanation:
Name the vertex of each angle the same as the angle letter. Name the intersection of the "horizontal" and "vertical lines" point Q.
Angle ZXQ is vertical to ∠x, so is the same measure.
Angle YQX is the value that makes the sum of angles in triangle XYQ be 180°. That is ...
∠YQX = 180° -51° -57° = 72°
This is also the measure of its vertical angle in the other triangle. Angle z is the sum of that vertical angle and 60°, so we have ...
∠z = 72° +60°
∠z = 132°
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Additional comment
The relations we used are ...
- vertical angles are congruent
- sum of angles in a triangle is 180°
- an exterior angle is equal to the sum of the remote interior angles