what are the 3 pathways to gain ATP?

Answer 1

Do you mean adenosine triphosphate? If so, this question doesn't belong in the tennis section (whoops!). (ATP also stands for Association of Tennis Professionals in men's tennis).

But, the pathways are: glycolysis, the citric acid cycle, and the electron transport chain.

Answer 2

first of all, you have to build up your ranking (ITN) by playing local and interstate tournaments. then you can start playing in futures tournaments, working your way up, then play on the satellite tour, work your way into the top 100 and you can start playing on the ATP (or WTA if you're a woman).