The part that gets me is the plane thing.

X + Y < 1

If x is 0 then Y is 0, -1, -2, -3 and so on right?

If y is 0 then the same applies for X =0, -1,-2, -3 and so on?

Please correct me if I am wrong.

Therefore How do I graph this? And what sets of numbers should I use?

00 for both won't work???