Hudson owns a food truck that sells tacos and burritos. He only has enough supplies
to make 100 tacos or burritos. He sells each taco for $3 and each burrito for $7.
Hudson must sell at least $420 worth of tacos and burritos each day. If a 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.