Answer:
C. 70°
Step-by-step explanation:
The inscribed angle marked 15° intercepts an arc that is double that measure, so the intercepted arc on the right is 2×15° = 30°.
The external angle marked 20° is half the difference of the intercepted arcs, so is ...
20° = (1/2)(x - 30°)
40° = x - 30° . . . . . . multiply by 2
70° = x . . . . . . . . . . . add 30°
The value of x is 70°.
