a firm plans to purchase at least 200 quintals of scarp containing high-quality metal X and low-quality metal Y. It decides that the scrap to be purchased must contain at least 100 quintals of X metal and not more than 35 quintals of Y metal.  The firm can purchase the scrap from two suppliers (A and B) in unlimited quantities. The percentage of X and Y metals in terms of weight in the scarp supplied by A and B is given below.

            Metals             supplier A                   supplier B

                 X                      25%                           75%                

                  Y                      10%                           20%

The price of A’s scrap is birr 200 per quintal and that of B is birr 400 per quintal. The firm wants to determine the quantities that it should buy from the two suppliers so that total cost is minimized.