>>13600565It's 7/8 anon.
Let's do it with real numbers in [0, 100] for simplicity, although the concept should work similarly in the case of integers, +- some edge cases.
Imagine a square plane with 0-100 on each axis, every point is a pair (x, y) in [1, 100]^2
We are interested in the area where x+y <= 50 for simplicity. If you draw it, you can easily see that this area is 1/8 of the total, the triangle between (0, 0), (50, 0), (0, 50)
See shitty hand drawn pic.
