Solving for Unknowns A contractor has to choose one of the following alternatives in his job: (a) buy a heavy-duty truck for $35,000. Salvage value is expected to be $8,000 at the end of the vehicle's 7-year depreciable life. Maintenance is $2500 per year. Daily operating expenses are $200. (b) Hire a similar unit for $550 per day. - Based on a 10% after-tax rate of return, how many days per year must the truck be used to justify its purchase over renting one? Base your calculations on straight-line depreciation and a 40% income tax rate. - Now the income tax rate is changed to 21%, what is your new