Question

Good evening everyone.........

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

Answer 1

Answer:

20

Step-by-step explanation:

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

Given that Price of a book is reduced by 5.

So, the reduced price = x - 5.

Given, Required price = 300.

According to the given condition,

$=>\frac{300}{x-5}-\frac{300}{x}=5$

$=>\frac{300x-300(x-5)}{x(x-5)}=5$

$=>\frac{300x-300x+1500}{x^2-5x}=5$

$=>\frac{1500}{x^2 - 5x}=5$

$=>1500 = 5(x^2 - 5x)$

$=>1500=5x^2 - 25x$

$=>5x^2-25x-1500 = 0$

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

$=>x^2-20x+15x-300=0$

$=>x(x-20)+15(x-20)=0$

$=>(x+15)(x-20)=0$

$=>x=-15,20$

Since, x cannot be negative.

Therefore, original cost price of book = 20

Hope it helps!

Answer 2

Step-by-step explanation:

x= list price

y= No of books

x*y = 300

(x-5)*(y+5) = 300

xy+5x-5y-25=300

5x-5y=25 ( as xy=300)

(5x-25)*x=5y*x ( multiplying “x” both sides)

5x²–25x=5*300

x²-5x=300

solving this quadratic equation , we will get

x=15 ,-20 ( -20 is not acceptable )

so, answer is 15