Question

If the list price of a book is reduced by rs. 5, then a person can buy 5 more books for rs. 300. the original cost of the book is

Answer 1

is question ka answer 330 he

Answer 2

Let the original list price of the book = Rs. x

Number of books bought for Rs. 300 = $\sf{\frac{300}{x}}$

Reduced list price of the book = Rs. (x-5)

Number of books bought for Rs. 300 = $\sf{ \frac{300}{x - 5}}$

A/C,

$\sf\red{\frac{300}{x - 5} - \frac{300}{x} = 5}$

$\longrightarrow$$\sf\red{300x - 300(x - 5) = 5x(x - 5)}$

$\longrightarrow$$\sf\red{300 \times 5 - 5x(x - 5) = 0}$

$\longrightarrow$$\sf\red{{x}^{2} - 5x - 300 = 0}$

$\longrightarrow$$\sf\red{(x - 20)(x + 15) = 0}$

$\longrightarrow$$\sf\red{x = 20 \: or \: x = - 15}$

As the price of the book cannot be negative, x ≠ -15 ,so x = 20

Hence, the original list price of the book = Rs. 20