Answer:
7
Explanation:
The sum of two interior angles in a triangle is equal to an
exterior angle that's complementary to the third interior angle
60 + 4 + 8x = 8 + 16x add like terms
8x + 64 = 16x + 8
64 - 8 = 16x - 8x
56 = 8x divide both sides by 8
7 = x