Answer:
17°
Step-by-step explanation:
∠AOC is a right angle, so it measures 90°
∠AOB and ∠BOC are in ∠AOC, so m∠AOB + m∠BOC = 90
m∠AOB = 73°
m∠BOC = x (shown in the diagram)
73 + x = 90
x = 17
∠AOC = 90
∠AOB + ∠BOC = ∠AOC
x = 90 - 73
