Question

) A shopkeeper buys a certain number of books from a publisher for 240. The
publisher gives him 4 more books for the same amount with a condition that the
shopkeeper would donate 2 per book to an orphanage

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Answer 1

Given: A shopkeeper buys a certain number of books from a publisher for 240. The  publisher gives him 4 more books for the same amount with a condition that the  shopkeeper would donate 2 per book to an orphanage.

To find: How many books did he buy?

Solution:

• Let the books bought for Rs 240 be x. Then the cost of each book would be 240/x .

• If the cost of each books were Rs 2 less then he can buy 4 more books

• Then he can buy x + 4 books  and cost of each book would be:

                    240/(x+4)

• According to the question, the equation formed is:

                    240/x - 240/(x+4) = 2

                     (240x + 960 - 240x)/(x² + 4x ) = 2

                    2 x² + 8x = 960

                      x² + 4x - 480 = 0

                    (x - 20)(x + 24) = 0

                    x = 20, -24

• Discarding -24, we get x = 20

Answer:

              So the shopkeeper bought 20 books.