ABC Logistics Inc. has four warehouses (A, B, C, and D) that require monthly shipments of 300, 350, 500, and 550 units per month, respectively. Its three plants (1, 2, and 3) have monthly capacities of 600, 450, and 650, respectively. Plant capacities, warehouse needs and shipping costs (in $) are shown in the following table. For example, the shipping cost from Plant 1 to Warehouse A is $15 per unit.