Answer:
s = 1
Explanation:
The sum of the interior angles of a polygon is
sum = 180° (n - 2) ← n is the number of sides
Here n = 5 , then
sum = 180° × 3 = 540°
sum the interior angles and equate to 540
39s + 129 + 79 + 145 + 148 = 540 , that is
39s + 501 = 540 ( subtract 501 from both sides )
39s = 39 ( divide both sides by 39 )
s = 1