RKE & Associates is considering the purchase of a building it currently leases for $30,000 per year. The owner of the building put it up for sale at a price of $170,000, but because the firm has been a good tenant, the owner offered to sell it to RKE for a cash price of $160,000 now. If purchased now, how long will it be before the company recovers its investment at an interest rate of 9% per year? Solve by using the NPER function.