What is the inverse of f (x)=ln3x-1

If  y  =  ln(3x) - 1.

There are two steps to find the inverse:

1)  Exchange x and y:

     x  =  ln(3y) - 1

2)  Solve for y:

     x + 1  =  ln(3y)

     e^(x + 1)  =  e^(ln(3y))

     e^(x + 1)  =  3y

     y  =  (1/3)e^(x + 1)