Answer:


Explanation:
Finding Angle B:
- Interior angles of a triangle add up to 180 degrees.
In ΔDBC,
98 + ∠B + 31 = 180°
∠B + 121 = 180
∠B = 180 - 121
∠B = 59°
Finding Angle A:
- The measure of exterior angle is equal to the sum of non-adjacent interior angles.
So,
∠C (Exterior Angle) = ∠A + ∠B
102 = ∠A + 59
- Subtract 59 from both sides
102 - 59 = ∠A
43 = ∠A
∠A = 43°
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