A shopkeeper buys a number of book for rupees 80. if he had bought 4 more books for the same amount each book would have cost rupees 1 less .how many books did he buy?
Answers
Let he bought x books for rs 80
So the cost of each book was 80/x
If the cost of each books were re 1 less then he can buy 4 more books
So, he can buy x+4 books
So the cost of each of the book would be
80/(x+4)
According to the question,
80/x-80/(x+4)=1
(80x+320-80x)/(x^2 +4x)=1
x^2+4x=320
x^2+4x-320=0
x^2+20x-16x-320=0
x(x+20)-16(x+20)=0
(x+20)(x-16)=0
Therefore, x= -20, 16
As x wouldnt be negative because quantity of book cant be negative so x=16
So he bought 16 books
Hope It helps you
Answer:
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