Jonathan owns a food truck that sells tacos and burritos. He only has enough supplies to make 90 tacos or burritos. He sells each taco for $3 and each burrito for $7. Jonathan must sell at least $420 worth of tacos and burritos each day. If xx represents the number of tacos sold and yy represents the number of burritos sold, write and solve a system of inequalities graphically and determine one possible solution.