A man bought a certain number of articles for $300.He sold all of them at $15 for a package of 4.If the total profit he made is the same as the original cost of 25 articles,how many articles did he buy?
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2008-10-04 5:31 am
回答 (1)
2008-10-04 5:52 am
✔ 最佳答案
Let no. of articles bought = x.Total selling amount = 15(x/4).
Cost per article = 300/x.
Therefore, cost of 25 articles = (300/x)(25) = 7500/x.
So Profit = Selling amount - total cost = 15x/4 - 300 = 7500/x. That is
15x^2 - 1200x - 30000 = 0
x^2 - 80x - 2000 = 0
(x - 100)(x + 20) = 0
x = 100. (x = -20 is rejected).
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