Question: Tilly needs to sell 100 bags at $10 per bag to make $300 in profit. How much did she buy each bag for? Think carefully first, then make a decision:

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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Tilly will make 100 x $10 = $1000 in total. She has spent $1000 - $300 = $700 on 100 bags. Each bag cost Tilly $700 / 100 = $7. So the answer is 7.