Use solver to answer the following question: A manufacturing concern wishes to minimize its shipping costs between its 4 factories and 3 warehouses. Factory 1 supplies 1000 units per week and costs $5, $3, and $4 to ship each unit to Warehouses 1, 2, and 3 respectively. Factory 2 supplies 1200 units each week and costs $4, $3, and $3 to ship to Warehouses 1, 2, and 3. Factory 3 supplies 1500 units and costs $6, $2, and $5 to ship to the three warehouses. Factory 4 supplies 1800 units and costs $6, $2, and $4. If Warehouse 1 requires 3000 units per week, Warehouse 2 demands 1000, and Warehouse 3 demands 1500, what is the minimum it would cost them in shipping to fulfill each warehouse's demand