Answer:
160°
Step-by-step explanation:
∠C and ∠D are both inscribed angles of arc AB. Therefore, they are equal.
5w + 20 = 7w − 4
24 = 2w
w = 12
Therefore, ∠C = ∠D = 80°.
Inscribed angles are half the central angle, so mAB = 2 × 80° = 160°.