Answer:
(b) 67.4°
Explanation:
You want the measure of angle 1 in the attached geometry.
Exterior angle
An exterior angle of a triangle is equal to the sum of the remote interior angles.
Application
In the bottom triangle, exterior angle 121.8° is equal to the sum of the remote interior angles 17.3° and ∠2. This means ...
∠2 = 121.8° -17.3° = 104.5°
In the top triangle, exterior angle ∠2 = 104.5° is equal to the sum of the remote interior angles 37.1° and ∠1. This means ...
∠1 = ∠2 -37.1° = 104.5° -37.1° = 67.4°
The measure of angle 1 is 67.4°.