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 $Rs. 500$?

$A$ man gains $15 \%$ by selling a calculator for a certain price. If he sells it at triple the price,then what will be the profit percentage (in $\%$)?

$A$ shopkeeper mixes $26 \, kg$ of wheat which costs $Rs. 20$ per $kg$ with $30 \, kg$ of wheat which costs $Rs. 36$ per $kg$ and sells the mixture at $Rs. 30$ per $kg$. Find the profit percent. (in $\%$)

Amit buys $5$ watches for $Rs. 9450$ and later sells them for $Rs. 9700$. How much profit does Amit make per watch in $Rs.$?

$A$ fan in a shop is offered at a discount of $10 \%$. It is sold during a clearance sale at an additional $6 \%$ discount over the already discounted price for $Rs. 846$. The original marked price of the fan is (in $Rs.$)

$A$ shopkeeper sold an article offering a discount of $5 \%$ and earned a profit of $23.5 \%$. What would have been the percentage of profit earned if no discount had been offered?