Answer:
6 sides
Explanation:
The interior angle and exterior angle sum to 180° , then
12x + 12 + 5x + 15 = 180
17x + 27 = 180 ( subtract 27 from both sides )
17x = 153 ( divide both sides by 17 )
x = 9
Then
exterior angle = 5x + 15 = 5(9) + 15 = 45 + 15 = 60°
The sum of the exterior angles of a polygon = 360° , thus number of sides n is
n = 360° ÷ 60° = 6