A book vendor sold a book at a loss of 10%. If he sold it for ₹ 1,080 more, he would have earned a profit of 10%. Find out the cost of the book.

Formula used:

Let the cost price (CP) of the book be ₹x.

Selling Price at 10% loss = CP - 10% of CP = x - 0.1x = 0.9x

Selling Price at 10% profit = CP + 10% of CP = x + 0.1x = 1.1x

Given that selling price at 10% profit is ₹1,080 more than the selling price at 10% loss:

1.1x - 0.9x = 1080

Calculation:

1.1x - 0.9x = 1080

⇒ 0.2x = 1080

⇒ x = 1080/0.2

⇒ x = 5400

∴ The correct answer is  (₹5,400).