3 Compute the payback period for each of these two separate investments: 125 points .. A new operating system for an existing machine is expected to cost $270,000 and have a useful life of six years. The system yields an incremental after-tax income of $77,884 each year after deducting its straight-line depreciation. The predicted salvage value of the system is $10,000 b. A machine costs $180,000, has a $14.000 salvage value is expected to last ten years, and will generate an after-tax income of $43,000 per year after straight-line depreciation Book Payback Patio Choose Denominator Choose Numator Payback Period Payback period