Ramesh purchased a bicycle for $Rs. 5200$ and spent $Rs. 800$ on its repairs. He had to sell it for $Rs. 5500$. Find out his profit or loss percent.

$A$ trader purchases a wrist watch and a pendulum for $Rs. 390$. He sells them making a profit of $10 \%$ on the watch and $15 \%$ on the pendulum. He earns a total profit of $Rs. 51.50$. The difference between the original prices of the pendulum and the watch is equal to? (in $Rs.$)

The cost price of $100$ books is equal to the selling price of $60$ books. The gain or loss percentage will be:

Oil equal to $20 \%$ of the weight of groundnut is extracted in a mill. The matter left after extraction is sold as cattle feed at the rate of $Rs. 12.5$ per $kg$. The groundnuts are bought at $Rs. 20$ per $kg$ and the processing cost is $Rs. 5$ per $kg$. At what price ($Rs.$ per $kg$) should the oil be sold to earn $20 \%$ profit on total costs (Total cost $=$ cost of groundnuts and processing costs)?

By selling an article at $80 \%$ of its marked price,a shopkeeper makes a loss of $10 \%$. What will be the profit percentage if he sells it at $95 \%$ of its marked price (in $\%$)?

$A$ trader sells his table at a profit of $15 \%$ and the chair at a loss of $7 \frac{1}{2} \%,$ but on the whole he gains $Rs. 50.$ If he sells the table at a loss of $7 \frac{1}{2} \%,$ and the chair at a profit of $15 \%,$ then he neither gains nor loses. Find the cost price of the table.