Formulate Objective Function (L.0.1): Teasley Delivery Company provides courier services. The company can deliver packages with its own equipment or can subcontract. Revenues from any delivery average $10 per item regardless of how the package was delivered. The company's fixed costs are $20,000 per month, which gives them the capacity to deliver 15,000 packages. Variable costs are $1.70 per package delivered using the company's own equipment. If Teasley subcontracts, the costs to deliver a package total $6.80.

Required: State, in mathematical form, Teasley Company's objective function.