The exterior angle is 151 degrees. The theorem states that the sum of its 2 remote interior angles, 5x+3 and 9x-20, will add up to this exterior angle. Therefore,
5x+3+9x-20 = 151 and
14x - 17 = 151 and
14x = 151 + 17
14x = 168 so
x = 12
If you want to find out the measure of each of these angles, just plug in 12 for x and do the math:
