Answer:
m∠XQZ = 72°
Explanation:
We presume the "if ..." condition is intended to mean that ray QY lies between rays QX and QZ. Then by angle addition, you get
∠XQY + ∠YQZ = ∠XQZ
(4a +8) + (28) = (8a)
36 = 4a . . . . . . . . . . . . . subtract 4a
72 = 8a = ∠XQZ . . . . multiply by 2