This one is relatively easy question because here LHS=RHS while in some question you will get ineq in st 1 n 2.
Try +ive, -ve and 0. Try values which will not result what you intend so that you can move on to next st.
Say here from 1 you knw that
x-y=2 so x is greater than y.
Lets move on to st 2
x=y^2-y; try y=0 and y =3 you will get 0 and 6 resp. Not suff.
I agree, it is not the best example for illustration since I couldn't find a good one at the point of posting. Maybe this one.
If x not equal -y, is (x-y)/(x+y)>1?
It can be quite tricky especially when there is 2 or more unknown variable and the unknown variables are numbers and not integers. We do have to consider fractions too, right? Also is there numbers I should avoid picking? Like number 1?