How can you find the value of p? Is the value of p for your parabola positive or negative? Explain. (Go to my other questions for the information)

James is playing his favorite game at the arcade. after playing the game 3 times, he has 8 tokens remaining. he initially had 20 tokens, and the game costs the same number of tokens each time. the number tt of tokens james has is a function of gg, the number of games he plays

Find the solution of this system of equation -7x+y=-20 9x-3y=36

Ineed to know the answer to this algebra question.