John decides to replace all his VHS with DVDs. He can trade in his VHS for $2 each and then buy the DVDs for $10 each. If he has 100 movies, how much does it cost to replace his movies? 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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It cost 10 - 2 = $8 to replace each movie. So it would cost 8 * 100 = $800 to replace everything. So the final answer is 800.