Question

If one book cost Rs 80, what is the cost of 900 Book?​

Answer 1

Answer:

cost of 900 books is 72000

Answer 2

Answer:

Let the shopkeeper buy x number of books.

According to the given condition cost of x books=Rs80

Therefore cost of each book = 80/x

Again when he had brought 4 more books

Then total books in this case =x+4

So cost of each book in this case = 80/x+4

According to Question,

80/x − 80/x+4

=1

80(x+4)−80x/x(x+4)

=1

x² +20x−16x−320=0

(x−16)(x+20)=0

x=16 or x=−20

Hence the shopkeeper brought 16 books

I HOPE IT HELPS :)