Question

By increasing the list price of a book by RS.10, a person can buy 10 less books. If price of book
is decreased by RS.6, he can buy 10 more books. Find the total amount and original price of the
book.​

Answer 1

Let original book price=X

Number of books that can be bought in 1200 =1200/x

Suppose price increases by 10. New price=x+10

No of books that can be bought in new price= 1200/(x+10)

Now, this number is 10 less than the no of books that can be bought in 1200 at ‘x’ price.

So, 1200/x= 1200/(x+10) + 10

Simplifying the above we get

X^2 +30x -1200=0

x=-b+-√b^2-4ac

x=30+-√900+4800/2

x=30 and -40

ignoring -40 as number should be positive.

So original book price is Rs 30