A feed company wants each feed bag that they produce to contain a minimum of 120 units of protein and 80 units of calcium. Corn contains 10 units of protein and 5 units of calcium per pound, and bone-meal contains 2 units of protein and 5 units of calcium per pound.
If corn costs 8 cents per pound and bone-meal costs 4 cents per pound, how much of each should they put in each bag, in order to minimize costs?