Answer:
#5 39 = x
Sides:
x - 15
2x
2x
Total of sides = 180
180 = (x-15) + 2x + 2x
180 = x - 15 + 4x
180 = -15 + 5x (add 15 to each side to remove -15)
195 = 5x (divide by 5 on each side to get x)
39 = x
#7 24 = x
Sides:
2x - 4
3x + 5
2x + 11
Total of sides = 180
180 = (2x - 4) + (3x + 5) + (2x + 11)
180 = 2x - 4 + 3x + 5 + 2x + 11
180 = 7x + 12 (subtract 12 to each side to remove 12)
168 = 7x (divide by 7 on each side to get x)
24 = x
#8 37 = x
Sides:
x
x + 4
3x - 9
Total of sides = 180
180 = (x) + (x + 4) + (3x - 9)
180 = x + x + 4 + 3x - 9
180 = 5x - 5 (add 5 to each side to remove -5)
185 = 5x (divide by 5 on each side to get x)
37 = x
Explanation: