Is it possible to find payback without tax for these set of numbers?

payback period = initial invest/annual cash flow

	Alternative 1	Alternative 2	Alternative 3
Cost of New Machine	$2,000,000	$3,500,000	$3,200,000
Estimated Useful Life	10 years	9 years	8 years
Operating Costs each year	$100,000	$225,000	$90,000
Warranty covers years 1-4	------	------	------
Maintenance Years 5-10	$20,000	$50,000	$60,000
Training for employees	$10,000	$0	$20,000
Expected revenues generated years 1-3	$500,000	$550,000	$450,000
Expected revenues generated years 4-6	$400,000	$400,000	$300,000
Expected revenues generated years 7-10	$250,000	$250,000	$200,000
Estimated Salvage Value	$30,000	$40,000	$20,000