Managed to solve it! Great work, accidentally used the first book thinking it was something else. I did however use internet just to look up some stuff. Was that allowed or am I a filthy cheater?
I've never had so much fun with functions. You managed to do something that none of my teachers or I could have done. Please make more levels and more types of functions. I would recommend writing the formula in math language if that's possible of course. 10/10 puzzle and if expanded further could be an extremely useful learning tool.
