subtracting binomials?

Question

(x - y) - (x + y)

How does this work? The answer is -2y

Answer 1

x-y -x-y=0x-2y
this is because the negitive sign at the front of the second brackets is the same as multiplying the bit inside by -1
then you collect your terms to find zero x's and -2 y's

Answer 2

basically you can only subtract like terms, so you subtract the x's and the y's to get -2

Answer 3

ok, you just multiply the terms in the second parenthesis per -1 so you get

x - y - x - y

and operating you get

-2y

because

x - x = 0

and

-y - y = -2y

hope this helps.