Exercise 24-5 Payback period computation; even cash flows LO P1 Compute the payback period for each of these two separate investments: a. A new operating system for an existing machine is expected to cost $280,000 and have a useful life of four years. The system yields an incremental after-tax income of $80,769 each year after deducting its straight-line depreciation. The predicted salvage value of the system is $11,000. b. A machine costs $170,000, has a $15.000 salvage value, is expected to last eleven years, and will generate an after-tax income of $44.000 per year after straight-line depreciation