Answer:
72
Explanation:
The exterior angle of a circle has the theorem divide in 2 the sum of the arcs on the circle. But when the angle has this form, it would always be 360/2 = 180 which is not true. When it take this form, you must divide the difference of the two arcs.
The circle has an arc of 108 leaving an arc of 252.
252 - 108 = 144
144/2 = 72