Easy problem... frustrated!

While trying to determine the inverse of (1) y = (1-2x) / (1+x), replace x with y and vice-versa.

(2) This gives x = (1-2y) / (1+y)

The goal is to isolate y in (2), a simple task... however I seem to have forgotten how to do such simple isolations. This part of the problem was skipped in my solutions manual.

The final answer is y = (1-x) / (2+x)

How would one go about solving for y from the original equation?

Thank you for your time.