Question

if the price of the book is reduced by Rs 5, a person can buy 5 more books for Rs 300. find the original list price of the book.

Answer 1

Answer:

Rs. 20

Step-by-step explanation:

Price of the book- x

• 300/x+5=300/(x-5)
• (300+5x)/x=300/(x-5)
• (300+5x)(x-5)=300x
• 300x-1500+5x^2-25x=300x
• 5x^2-25x-1500=0
• x^2-5x-300=0
• x=20

Original price is Rs. 20

Answer 2

Solution -

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

New Price list = Rs. x - 5

Let the original number of books bought be k.

New number of books bought = k + 5

So,

Total amount spent innitially -

=> Rs. kx

Now,

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

=> xk + 5x - 5k - 25 = 300

Substuting Values -

=> 5 ( x - k ) = 25

=> x - k = 5

So, k = x - 5

xk = 300

=> x( x - 5 ) = 300

=> x ^ 2 - 5x - 300 = 0

=> x ^ 2 - 20x + 5x - 300 = 0

=> x ( x - 20 ) + 5 ( x - 20 ) = 0

=> ( x + 5 )( x - 20 ) = 0

As x can not be negative, the value of x is 20.

Hence the Original List Price of the book is Rs. 20.

Answer -

The Original List Price of the book is Rs. 20.

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