Two alternatives are under consideration. The first alternative will cost $100,000, require $20,000 in maintenance and operation costs each year, and a life cycle of 4 years. The second alternative will cost $300,000, require $5,000 in maintenance and operation costs each year and a life of 6 years. Neither option will have a salvage value. In order to compute the present worth or future worth, how many years of each alternative should I use to accurately compare the two alternatives.