A shop keeper buys a number of books for Rs.80. If he had bought 4 more books for the same amount, each book would have cost his Rs.1 less .How many books did he buy?

Explanation

Let `x` is the number of books that the shopkeeper purchased.

Then, price of each book ` = 80/x` Rs

If he had bought `4` more books, then each book would have cost `1` rs less.

So, he can buy `x+4` books in the same amount.

So the cost of each of the book would be
`80/(x+4)`.

According to the question,

`80/x-80/(x+4)=1`

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