Aditya purchase a book with a $20 \%$ discount on the marked price. How much $Rs.$ did he pay if the book marked was $Rs.$ $500 ?$

On an order of $5$ dozen boxes of a consumer product, a retailer receives an extra dozen free. This is equivalent to allowing him a discount of........$\%$

A man sells two article for $Rs.\,5000$ each neither losing nor gaining in the deal. If he sold one of them at a gain of $25 \%,$ the other article is sold at a loss of.......$\%$

A man buys an article for $10 \%$ less than its value and sells it for $10 \%$ more than its value. His gain or loss percent is

A shopkeeper buys $144$ items at $90$ paisa each. On the way $20$ items are broken. He sells the remainder at $RS.\,1.20$ each. His gain percent correct to one place of decimal is

The marked price of an article is $Rs.\, 5000.$ But due to a special festive offer a certain per cent of discount is declared. Mr. $X$ availed this opportunity and bought the article at reduced price. He then sold it at $Rs.\, 5000$ and thereby made a profit of $11 \frac{1}{9} \%$. The percentage of discount allowed was