Colton owns a food truck that sells tacos and burritos. He only has enough supplies to make 120 tacos or burritos. He sells each taco for $3.75 and each burrito for $6. Colton must sell at least $540 worth of tacos and burritos each day. If z represents the number of tacos sold and y represents the number of burritos sold, write and solve a system of inequalities graphically and determine one possible solution.