Answer:
40°
Explanation:
Given the following
∠AOC = 108°
∠AOB = 3x + 4°
∠BOC = 8x - 28
∠AOC = ∠AOB+∠BOC
108 = 3x+4+8x-28
108 = 11x-24
11x = 108+24
11x = 132
x = 132/11
x = 12
Next is to get ∠AOB. Recall that:
∠AOB = 3x+4
∠AOB = 3(12)+4
∠AOB = 36+4
∠AOB = 40°
Hence the measure of ∠AOB is 40°