9. Steel mills in three cities produce the following amounts of steel. These mills supply steel to four cities where manufacturing plants have the following demand. Shipping costs per ton of steel are as follows. Because of a truckers' strike, stipments are at present prohibited from Birmingham to Chicago. a. Set up a transportation talleau for this problen and determine the initial solotion. Ifentify the method used to find the initial solution. b. Solve this problem using MODI. c. Are there multiple optimal solutions? Explain. If so, identify them. d. Formulate this problem as a general linear programming model