Ashipping company employee is in charge of packing cargo containers for a shipment. he knows a certain cargo container cargo container can hold a maximum of 50 microwaves or a maximum of 15 refrigerators. each microwave takes up 6 cubic feet of space, and each refrigerator takes up 20 cubic feet. the cargo container can hold a maximum of 300 cubic feet. the employee is trying to figure out how to pack a container containing both microwaves and refrigerators. which one of the following systems of inequalities can the employee use to determine how many of each item (microwaves, m, and refrigerators, r) he can pack into one cargo container?