to find inverse, i'm pretty sure you have to exchange the Y with the X, and then solve for Y.
solve for y:
<----move the denominator on the right to the left
<----move all the y's to one side and the single x to the other
<----factor out the 2y from the left side
<----get the 2y by itself
<----get the y by itself
EDIT: I think my way is easier, pickslides...