You can purchase an optical scanner today for $410. The scanner provides benefits worth $65 a year. The expected life of the scanner is 10 years. Scanners are expected to decrease in price by 20% per year. Suppose the discount rate is 11%. When is the best time to purchase the scanner? (Round your answer to the nearest cent.)

PV is maximized when you wait _________ years to purchase the scanner. At this date NPV will be equivalent to $ _______ today.

i got it 5year=141.54 and 6 year=149.46, but it is wrong answer, i dont know which step wrong. plz show the work detail.