Question

what is the measure of the missing angle?

Answer 1

115 degrees because according to the triangle sum theorem, the inside angle so 65 degrees. Then since it is a straight line it equals 180. 180-65=115

Answer 2

40 + 75= 115
180 - 115= 65
The interior missing angle is 65
You can use that to find the exterior angle
Unfortunately I forgot how to do that. 
I hope I
 was at least a bit helpful