Question

By increasing the prise of a book by rs.10 a person can buy 10 books less for rs.1200.Find the original price oh the book.

Answer 1

Let the original price of the book be= x
and let the actual no of books be= y 

So, xy=1200
=>y=1200/x

By increasing the price of a book by rs.10, present price = x+10

number of books can be bought for the new price = 1200/(x -10) = (1200-10x)/x

so, the equation is,

x+10 (1200-10x / x) = 1200

if we solve the equation we will get x=30

So, the list price of the book is Rs 30.

Answer 2

Let the original price of the book be= x
and let the actual no of books be= y 

So, xy=1200
=>y=1200/x

By increasing the price of a book by rs.10, present price = x+10

number of books can be bought for the new price = 1200/(x -10) = (1200-10x)/x

so, the equation is,

x+10 (1200-10x / x) = 1200

if we solve the equation we will get x=30

So, the list price of the book is Rs 30.