How is the Present Value

How is the Present Value of a business computed based on the following
facts:
Lease Termination: December 31, 2019
Present Value Date: March 1, 2007
Lease Term (years): 12.84
Annual Net Income Past 3 years: $331,587 (Assume 0% annual increase)

Results were as Follows:
Present Value of Annual Net Income @ 25.0% Return $1,250,847
Present Value of Annual Net Income @ 22.5% Return $1,364,976
Present Value of Annual Net Income @ 20.0% Return $1,498,504
Present Value of Annual Net Income @ 17.5% Return $1,656,001