a plumbing manufacturer makes two lines of bathtubs, model a and model b. every tub requires blending a certain amount of steel and zinc; the company has available total of 24,500 pounds of steel and 6,000 pounds of zinc. each model a bathtub requires a mixture of 120 pounds of steel and 20 pounds of zinc, and each yields a profit of $90. each model b tub produced can be sold for a profit of $70; it requires 100 pounds of steel and 30 pounds of zinc. to maintain as adequate supply of both models, the manufacturer would like the number of model a tubs made to be no more than 5 times the number of model b tubs. fine the best product mix of bathtubs.