Question

If f(x)=3x-15, then f^-1(x) = solve for x please

Answer 1

1.  Replace f(x) with y:  y = 3x - 15
2.  Interchange x and y:  x = 3y - 15
3.  Solve this for y:  3y = x + 15, and y = (x + 15)/3
4.  Replace y with 

   -1                -1
 f   (x):           f   (x) = (x + 15) / 3            (answer)