using excel solver

5. There are 4 possible warehouse locations (W1 to W4). W1 and W2 would cost \$5M and last for 10 years and have capacities of 125,000 units per year. W3 and W4 would cost $6M and last for 10 years and have capacities of 150,000 per year. The firm uses an interest rate of 15%. The warehouses would supply 6 retailers (R1 to R6) with annual demands of 50,000 for R1 to R3 and 60,000 for R4 to R5. Per unit processing cast at the warehouse is $4 at W1 and W2 and $3.50 at W3 and W4. Transportation costs (per unit) are shown in the table below. Write out the (clearly defining your variables) and solve using a solver (e.g., Excel)