To get from (2x - 3y) to (x - 2y), we need to subtract x from 2x and add 2y to -3y. Therefore, we need to add (x - 2y) - (2x - 3y) to (2x - 3y) to get (x - 2y).
Simplifying (x - 2y) - (2x - 3y), we have:
(x - 2y) - (2x - 3y) = x - 2y - 2x + 3y = -x + y
Therefore, we need to add (-x + y) to (2x - 3y) to get (x - 2y).
Simplifying (2x - 3y) + (-x + y), we have:
(2x - 3y) + (-x + y) = 2x - 3y - x + y = x - 2y
So, we need to add (-x + y) to (2x - 3y) to get (x - 2y).
Therefore, the answer is (B) y - x.