Hey!

If you do figure it out, can you share the answer?

Good luck!
First off, the number on the right side in the top right square looks like a 6 but should be a 5 (which made finding an answer even harder).
In each square subtract the sum of the horizontally opposed numbers from the product of the vertically opposed numbers, you get 40.
(5x13) - (5+20) = (4x12) - (3+5) = (4x16) - (4+20) = (5x11) - (7+8)

I ended up using google after giving up ...