Question

sanvi purchase some books for rupees 120 if she purchased three more books for the same amount each book would have cost rupees two less.find the number of books purchase by Sanvi and price of each book ​

Answer 1

Let the no. of books purchased by Sanvi be "x".

So,

The cost of each book = Rs. [120/x]

the no. of book that shanvi will have (x+3)

so the cost of each book will be

[120/(x+3)]

by the equation 1 and 2

[120/x] - [120/(x+3)] = 2

120 [(x+3-x)/x(x+3)] = 2

60 [3/(x^2+3x)] = 1

180 = x² + 3x

x^2 + 3x -180 = 0

x² + 15x - 12x - 180 = 0

x(x+15)-12(x+15)

(x-12) (x+15)

x = -15

x= 12

so The cost of each book = 120/x = 120/12 = Rs. 10