Question: I figured 2 years for the payback period. Should i be looking at months or just 2 years on both machine A and B? The question just says "compute the payback period for each of the 2 machines". Here's the data and my work shown below:

Maryville Cleaners has the opportunity to invest in one of two dry cleaning machines.Machine A has a four-year expected life and a cost of $30,000.It will cost an additional $6,500 to have the machine delivered and installed, and the expected residual value at the end of four years is $4,000.Machine B has a four-year expected life and a cost of $55,000.It will cost an additional $7,000 to have machine delivered and installed, and the expected residual value at the end of four years is $6,000.The company has a required rate of return of 14 percent.Additional cash flows related to the machines are as follows: