CBSE Class 10 Answered

Let the price of 1 book be x.

Let the persons buys n number of books in Rs.300

When the price of the book is reduced by Rs5, new price of the book x' = x -5

The person can buy n+3 books.

Now according to the first condition,

nx = 300

According to the second condition,

(n+3)(x-5) = 300

((300/x)+3) (x-5) = 300

(300+3x)(x-5) = 300x

3x² -15x - 1500 = 0

x² -5x - 500 = 0

(x - 25) (x+20) = 0

x = 25 or x = -20

Since the price can never be negative so the original cost of the book is Rs 25.