It costs $300 to buy a lawn mower from a lawn supply store. Assume that you can keep a lawn mower for at most five years and that the estimated maintenance cost each year of operation is as follows: year 1, $90; year 2, $135; year 3, $175; year 4, $200; year 5, $250. You have just purchased a new lawn mower. Assuming that a lawn mower has no salvage value, determine the strategy that minimizes the total cost of purchasing and operating a lawn mower for the next 10 years.