A) 1, 4, 9, 16, 25, 36, 49, 64, 81, 100
B) 36 + 64 = 80
C) 36 - 25 = 11
X^3 + h^3 - 3x-3h - x^3 +3x h^3 - 3h h^2 - 2h
------------------------------------- = ------------------ =
h h
I found this online I hope it helps a little if not, then sorry.
50/x = tan(12°)
x = 50/tan(12°) ≈ 235 . . . . ft