Decision Variables Let's define the following decision variables for the number of trucks leased under different lease lengths for each month: 1 x 1m : Number of trucks leased in month m under a 1-month lease, where = 1 , 2 , 3 , 4 m=1,2,3,4. 2 x 2m : Number of trucks leased in month m under a 2-month lease, where = 1 , 2 , 3 , 4 m=1,2,3,4. 3 x 3m : Number of trucks leased in month m under a 3-month lease, where = 1 , 2 , 3 , 4 m=1,2,3,4. 4 x 4m : Number of trucks leased in month m under a 4-month lease, where = 1 , 2 , 3 , 4 m=1,2,3,4. These decision variables represent how many trucks are leased each month under each type of leasing contract. Parameters Truck requirements per month: Month 1: 10 trucks Month 2: 12 trucks Month 3: 14 trucks Month 4: 8 trucks Company trucks available: Month 1: 1 truck Month 2: 2 trucks Month 3: 3 trucks Month 4: 1 truck Cost of short-term leases: 1-month lease: $4000 per month per truck 2-month lease: $3700 per month per truck 3-month lease: $3225 per month per truck 4-month lease: $3040 per month per truck Long-term lease cost (monthly): Long-term lease: $600 per truck per month for trucks already owned Truck drivers (long-term lease): $20/hour 8 hours/day 5 days/week 4 weeks = $3200 per month per truck Fuel cost: $100/day 5 days/week 4 weeks = $2000 per month per truck Total cost per truck under long-term lease: $600 + $3200 + $2000 = $5800 per month per