Marriott Tub Company manufactures two lines of bathtubs, called model A and model B.
Every tub requires a certain amount of steel and zinc
; the company has available a total of 25,000 pounds of steel and 6,000 pounds of zinc.
Each model A bathtub requires a total of 125 pounds of steel and 20 pounds of zinc, and each yields a profit of $90.
Each model B bathtub can be sold for a profit of $70;
it in turn requires 100 pounds of steel and 30 pounds of zinc. Find the best production mix of the bathtubs.