Two alternate exterior angles are formed by a transversal through two parallel lines. If one of these alternate exterior angles has an angle measure of 5x-21, and the other angle has a measure of 2x+12, then what is the sum of their angle measures?

SUM = 114+66 = 180

Explanation:

The sum of the two exterior angles is 180° because the two exterior angles are lying on a straight line and straight line is 180°.

So,

(5x-21) + (2x+12) = 180°

5x-21+2x+12 = 180

5x + 2x - 21 + 12 = 180

7x - 9 = 180

7x = 189

x = 189/7 = 27

So

5x-21 = (5*27) - 21 = 135 - 21 = 114

2x+12 = 2 * 27 + 12 = 54+12 = 66

SUM = 114+66 = 180