The distribution system for a company consists of two plants, two warehouses and three customers. Plant capacities and shipping costs per unit (in $) from each plant to each warehouse are as follows: Warehouse W1 W2 Capacity Plant P1 7 2 650 P2 8 1 450 Customer demand and shipping costs per unit (in $) from each warehouse to each customer are Customer C1 C2 C3 Warehouse W1 6 3 - W2 5 - 8 Demand 310 270 420 Due to technical reasons items cannot be shipped from Warehouse-1 to Customer-3 and from Warehouse-2 to Customer-2 temporarily. In addition, direct shipments can be made from Plant-1 to Customer-1 at a cost of $4 per unit. Shipments can be made between the warehouses at a cost of $2 per unit. Draw a network representation and formulate a linear programming model to minimize the total shipping costs for this problem.