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A shopkeeper buys a number of books for 80. If he had bought 4 morebooks for the same amount, each book would have cost 1 less. Howmany books did he buy? |
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Answer» Let shopkeeper buy n books Then cost of one book = 80/n If he bought 4 more books, then cost of one book = 80/(n+4) As per given condition 80/(n + 4) = 80/n - 180(n + 4 - n) = n(n+4)n^2 + 4n - 320 = 0n^2 + 20n - 16n - 320 = 0n(n + 20) - 16(n + 20) = 0(n - 16)(n + 20) = 0n = 16, - 20 Therefore number of books are 16 |
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