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

$A$ person sells $36$ apples per rupee and suffers a loss of $4 \%$. Find how many apples per rupee should be sold to have a gain of $8 \%$.

$A$ man purchases some oranges at the rate of $3$ for $₹ 40$ and the same quantity at $5$ for $₹ 60$. If he sells all the oranges at the rate of $3$ for $₹ 50$,find his gain or loss percent (to the nearest integer).

If the cost price of an item is $\frac{2}{5}$ of its marked price and if it is sold at a discount of $10 \%,$ then there will be

$Mr.$ $A$ sold goods to $Mr.$ $B$ at a $10\%$ discount on the printed rate. The discounted value is $Rs. 1242$. If a $15\%$ profit is earned on the purchase rate by selling the goods at the printed rate,what is the purchase rate? (in $Rs.$)

$A$ shopkeeper allows a discount of $10\%$ on the marked price of an item but charges a sales tax of $8\%$ on the discounted price. If the customer pays $Rs. 3,402$ as the price including the sales tax,then the marked price is (in $Rs.$)