Question

a shopper buys some books for Rs 80, if he had bought 4 more books for the same amount. each book would have cost Rs 1 less. find the number of books he bought​

Answer 1

Step-by-step explanation:

Let the number of books bought by the shopkeeper be x.

Price of x books =Rs.80

⇒ Price of 1 book = 80/x

--- (1)

Now, if the number of books had been (x+4)

Price of x+4 books =80

⇒ Price of 1 book= 80/x+4

--- (2)

Now, according to the question, equation (1) - (2) =1.

i.e., 80/x - 80/x+4 =1⇒ 320/x²+4x =1

x²+4x−320=0

⇒x²+20x−16x−320=0

⇒x(x+20)−16(x+20)=0

⇒(x−16)(x+20)=0

⇒x=16 or x=−20. But number of books can never be −ve.

Therefore number of books he bought =16.

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