If you have three of them, they go in order: 2, 3, 4 and so on.
If the lowest is X then the next two are x + 1 and x + 2.
Though the question asks you to look for the highest, so I'll call that x, so the other two become "x - 1" and x - 2
So if we add them up to get 36, we get:
x + (x - 1) + (x - 2) = 36
Solving for x:
3x - 3 = 36
3x = 39
x = 13
