Answer:
sum_of_interior_angles = (number_of_sides - 2) x 180° → if number_of_sides is 21: sum = (21 - 2) x 180° = 19 x 180° = 3420°
Step-by-step explanation:
Answer: 3420 degrees
Explanation: You use the formula 180(n-2) with n = 21 to find the answer above.
