1. Steel mills in three cities produce the following amounts of steel: Location A. Bethlehem B. Birmingham C. Gary Weekly Production (tons) 150 210 320 680 These mills supply steel to four cities, where manufacturing plants have the following demand: Location 1. Detroit 2. St. Louis 3. Chicago 4. Norfolk Weekly Demand (tons) 130 70 180 240 620 Shipping costs per ton of steel are as follows: To (cost) From 1 2 3 4 ABC $14 $ 9 $16 $18 11 8 7 16 16 12 10 22 Because of a truckers' strike, shipments are prohibited from Birmingham to Chicago. Formulate this problem as a linear programming model and solve it by using the computer.