Answer:
156 dergrees
Step-by-step explanation:
Each triangle has an angle sum of 180 degrees, so the sum of the interior angles of the 15 must be 13 × 180 = 2340 degrees. Since the 15 is regular, this total is shared equally among the 15 interior angles. Each interior angle must have a measure of 2340 ÷ 15 = 156 degrees.