Question

a shopkeeper buys a number of books for rs 80 if he had bought 4 more books for the same amount it books would have cost rupees 1 less how many books did he buy

Answer 1

Let the number of books = x

Amount for x books = ₹80

80/x

If he buys 4 more books = x+4

80/x+4

So,

80/x - 80/x+4 = 1

x=16 and not -20 because number of books cannot be -ve.

number of books bought = x+4

=16+4 = 20books

Therefore, he bought 20books.

Answer 2

Eq no 1:- total books purchased = x

Therefore unit price = 80/ x

Eq no 2:- 4 extra book purchased on same price = ×+4 =80

Therefore unit price = 80/(×+4)

Difference of price is Rs. 1

Hence 80/× - 80/(x-4) =1

By solving the equation

320/ (xpower2 + 4x)=0

Xpower2+4x-320=0

X(X+20) -16(X+20)=0

(X+20) (X-16)=0

X=-20, X=16

We negate negative answer

Therefore no of books brought =16