Question

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

Answer 1

let total no. of books = K
total money = 80£
Ac/ Q
80/K = 80/(K+4)+1
80/K = (80+K+4)/(K+4)
80(K+4) = K(84+k)
80K +320 = 84K + K^2
K^2 + 4K -320 = 0
K^2 + 20k - 16k - 320 = 0
(K- 16)(K+20) =0
K-16 = 0
K = 16£ Ans

Answer 2

Answer:

VarghesebijupbaxnsHelping Hand

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