For all non-zero real numbers x and y such that x – y = xy, 
- 0
- -1
- y – x
Hang on here. First of all, are there any numbers such that x – y = xy?
Well, x – y = xy → x – xy = y → x(1 – y) = y → x = 
.
If y = 3, say, then x = 
.
Checking, x – y = 
.
And, xy = 
.
Okay, there are such numbers, so let�s figure out the answer:
.
The answer is (d).