Answer:
80°
Explanation:
The sum of interior angles for this rectangle is equal to (s - 2)×180 (s being the number of the sides)
(4-2)×180 = 360
Two of the given sides are 90° and the other one is 50+50 = 100 so the measure of angle 1:
90 + 90 + 50 + 50 + ∠1 = 360 add all given angles
280 + ∠1 = 360 subtract 280 from both sides
∠1 = 80