solve for x

(x/1-x)^2 - (x/1-x) -6 = 0

let u = x/(1-x). Then you have

u^2-u-6=0
(u-3)(u+2) = 0

So, you have
x/(1-x) = 3
x = 3-3x
x = 3/4

or

x/(1-x) = -2
x = -2+2x
x = 2