I'm assuming the crazy arrows are simply a ruse, since any number can trace a patch to any slot.
Given {1 2 3 4 5 + =} you know a few things:
The equation has to be of the form _ _ + _ = _ _.
-- There is no way involve a 3-digit number because it won't fit in the 7 total slots.
-- There is no way to involve 2 two-digit numbers because they won't fit.
-- There is no way to involve 2 one-digit numbers because you won't use all 7 slots.
Since the largest numbers are 4 and 5, we know that you can't have any carry over into the tens column. X4 + 5 = X9. Thus, we have to reuse the tens digit in the two-digit number.
It is after 5 pm.
I cannot solve this.
I feel retarded.
Edit: Maybe it's expecting postfix notation?