n=7; x=--n-n---; and y=(n--)-(--n);

Question

plese tell me how to solve

Answer 1

x = 0
y = 2

when you have --n you decrement the value of n and then consider it into your operation. (so, if you have --5, you consider 4)
when you have n-- you consider it, and THEN you decrement it. (so, if you have 5--, you consider it 5, but the next find you find it, it'll be a 4)

don't take that as 100% sure though. might be wrong since I'm not sure if increment and decrement's order is ruled by parenthesis.