Steel mills in three cities produce the following amounts of steel:

Location                             Weekly Production (tons)

A. Bethlehem                                     150
B. Birmingham                                   210
C. Gary                                               320
                                                            680

These mills supply steel to four cities, where manufacturing plants have the following demand:

Location                                 Weekly Demand (tons)
1. Detroit                                             130
2. St. Louis                                            70
3. Chicago                                           180

4. Norfolk                                            240

                                                            620

Shipping costs per ton of steel are as follows:

                                        

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.