Mohit lost $18 \%$ by selling a bicycle for $Rs. 1230$. What percent shall he gain or loss by selling it for $Rs. 1600$?

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 $Rs. 500$?

$A$ trader mixes $26 \text{ kg}$ of rice at $Rs. 20$ per $\text{kg}$ with $30 \text{ kg}$ of rice of another variety at $Rs. 36$ per $\text{kg}$ and sells the mixture at $Rs. 30$ per $\text{kg}$. His profit percent is:

$A$ man purchased $150$ pens at the rate of $Rs. 12$ per pen. He sold $50$ pens at a gain of $10 \%$. The percentage gain at which he must sell the remaining pens so as to gain $15 \%$ on the whole outlay is........$\%$

$A$ man sells two articles,each for $Rs. 640$. He earns $20\%$ profit on the first and $40\%$ profit on the second. Find his overall percent profit.

$A$ man buys $10$ oranges for a rupee and sells $8$ oranges for a rupee. What is the profit percent?