The Northern Iron Company must decide how many tons of pure steel (x) and how many tons of scrap (y) to use in preparing an alloy for a customer. The cost per ton of pure steel is 3 and that of scrap is 6 (due to impurities); the client's demand is at least 5, and he would accept more if required. The availability of x is 4 tons and 7 that of (y). The ratio between scrap and pure steel cannot exceed 7/8. The factory has 18 hours available to melt and cast; a ton of pure steel requires 3 hours, while scrap only 2 hours. Please use the simplex method with all tables