John's hair grows 1.5 inches every month. Every time it gets to 9 inches long he cuts it down to 6 inches. A haircut costs $45 and he gives a 20% tip. How much does he spend on haircuts a year? Give me reasons, before answering the question

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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He cuts off 9 - 6 = 3 inches when he gets a haircut. That means he needs to cut it every 3 / 1.5 = 2 months. So he gets 12 / 2 = 6 haircuts a year. He gives a 45 * .2 = $9 tip. So that means each hair cut cost 45 + 9 = $54. So he pays 54 * 6 = $324 a year. So the final answer is 324.