\(f(x) = \frac{cx}{(4x-5)(3x+2)}\)
\(f(f(x)) = f(\frac{cx}{(4x-5)(3x+2)})\)
\( f(\frac{cx}{(4x-5)(3x+2)}) = \frac{c(\frac{cx}{(4x-5)(3x+2)})}{(4(\frac{cx}{(4x-5)(3x+2)})-5)(3(\frac{cx}{(4x-5)(3x+2)})+2)}\)
\( x = \frac{c(\frac{cx}{(4x-5)(3x+2)})}{(4(\frac{cx}{(4x-5)(3x+2)})-5)(3(\frac{cx}{(4x-5)(3x+2)})+2)}\)
\(a = \frac{cx}{(4x-5)(3x+2)}\)
\( x = \frac{ca}{(4a-5)(3a+2)}\)
Blahblahblah, you are eventually gonna end up with c = (4x-5)(3x+2), I think.. then just plug it in!