Question

A

Answer 1

since you are given the amount of 62.10, all you have to do is substitute it to the given equation with P=62.10 so you'll have
P = (20 + 0.5x) + 0.15(20 + 0.5x)
62.10 = (20 + 0.5x) + 0.15(20 + 0.5x)
solve for x

Answer 2

removing parenthesis and distributing 0.15 you'll have
62.10 = 20 + 0.50x +0.15(20) + 0.15(0.5x)
62.10 = 20 + 0.50x +3 + 0.075x
62.10 -20 - 3 = 0.50x + 0.075x
39.10 = 0.575x
x = 68 pages