So here is my math problem - I think it was supposed to be just straightforward factorising, but since it isn't a generic quadratic equation (or maybe it is haha, I can't tell if it is, in this form!) I can't work out how to factorise right down to the answer the book says. Here is the problem.

(x - 3)

Factorise the expression^{2}- (y - 2)^{2}

The answer is apparently: (x + y - 5)(x - y - 1)

but the only thing I could work out how to do was: (x - 3)(x - 3) - (y - 2)(y - 2)

Please explain how one would reach the correct answer?