Lupe is the manager of the football team, and she has to plan a team dinner for Saturday night. She knows that one large pizza can feed 3 players and one sandwich tray can feed 4 players. Lupe needs to order enough food for the 72 players on the team. (a) Write a linear equation to represent the number of pizzas (x) and the number of sandwich trays (y) she could purchase to feed the football players.