g(x) is the inverse of f(x)


Her fastest change in elevation was -200 feet in 10 minutes. She was going at a rate of 20 fpm (feet per minute) compared to 15 fpm.
Y = -5x + 9
y = 5x + 7
5x + 7 = -5x + 9
5x + 5x = 9 - 7
10x = 2
x = 2/10 reduces to 1/5
y = 5x + 7
y = 5(1/5) + 7
y = 1 + 7
y = 8
solution is (1/5,8)