Compute the payback period for each of these two separate investments: a new operating system for on 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. A machine costs $210, 000, has a $14,000 salvago value, is ox pooled to last seven years, and nil generate an after-tax income of $43,000 per year after straight-line depreciation