A fertilizer manufacturer has orders for 900 tons of a certain fertilizer from Chicago, Illinois, and 600 tons from Omaha, Nebraska. The company has 1,050 tons of this fertilizer in a warehouse in Springfield, Missouri, and 1,200 tons in a warehouse in Madison, Wisconsin. It costs $10 to ship a ton of the fertilizer from Springfield to Chicago, and the cost to ship a ton from Springfield to Omaha is $20. The shipping cost per ton is $8 from Madison to Chicago, but it costs $15 per ton to ship from Madison to Omaha. If the fertilizer manufacturer’s objective is to minimize the total shipping costs from each warehouse to each destination:

1. Formulate this problem as a linear programming problem.

2. Solve this problem using Excel Solver, and provide the optimal solution values of all variables.