[(4x+6 / 3x-1) + 6 ] / [(12x+18 / 9x-3) -4]

I tried to format it the best way I could... on my paper, it looks more like:

4x+6

----- +6

3x-112x+18

------- -4

9x-3

I can't figure this out for the life of me..

I am trying to prove that these are inverse. So I want the whole thing to equal x.

I don't know what this process is called.. but I just know I have to do the

f(x) of f^-1(x)

then

f^-1(x) of f(x)