Wheat is harvested at farms in Nebraska and Colorado before being shipped to three grain elevators in Kansas City, Omaha, and Des Moines. The amount of wheat harvested at each farms is 300 tons. The wheat is then shipped to mills in Chicago, St. Louis, and Cincinnati with demands of 100, 200, and 300 tons, respectively. Per unit shipping costs are as follows. From/To Kansas City Omaha Des Moines Nebraska $16 $10 $12 Colorado $15 $14 $17 From/To Chicago St. Louis Cincinnati Kansas City $6 $8 $10 Omaha $7 $11 $11 Des Moines $4 $5 $12 Identify a distribution plan that minimizes distribution cost.