Josie received $50 as a gift. She plans to buy two cassette tapes that cost $9 each and a headphone set that costs $25. How much money will she have left? 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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The cassette tapes will cost 2 × 9 = $18. She spends 18 + 25 = $43 in total. Josie will have 50 - 43 = $7 left. So the final answer is 7.