Answer:
120
Step-by-step explanation:
x=7/5
x - 7/9 = f(x)^-1
f(x) = 9x + 7
y - 7 = 9x
y - 7/9 = 9x/9
Interchange!
x - 7/9 = y
1) PN
2) MN
3) 8
4) 8