Using an impulse response and an output to find an input using Z-transform

ztjust

1. The problem statement, all variables and given/known data
An LTI digital system with impulse response h[n] = 2(1/4)^n u[n-1] produces an output y[n] = (-3)^n u[n-1]. Determine the corresponding input x[n].


2. Relevant equations

I believe that Y[z] = X[z]H[z]



3. The attempt at a solution

So I started by finding the z-transform of h[n]. Which I think is (0.25z)/(z-0.25)^2.

I then went on the find to the z-transform of y[n]. Which I think is z/(z+3).

So then I divided them and got 4((z-0.25)^2) / (z+3)..

I can't figure out how to take the inverse z-transform to get x[n]. I think my z-transforms might be wrong, or I'm just dividing incorrectly.