$A$ shopkeeper buys a toy at $Rs. 100$ and sells it at $Rs. 125$. Another shopkeeper buys the same toy at $Rs. 125$ but sells it at $Rs. 100$. What are the respective profit and loss percentages for the two shopkeepers?

$A$ 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 $8 \%$.

If the selling price of $\frac{2}{3}$ of a certain quantity of milk is equal to the cost price of the whole quantity of milk,then what will be the gain percent in this transaction?

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)?

$A$ wholesaler had $200$ dozens of mangoes. He sold some of these mangoes at $20 \%$ profit and the rest at $10 \%$ profit,so that he made $13 \%$ profit on selling all the mangoes. How many mangoes (in dozens) did he sell at $20 \%$ profit?

$A$ person sells two articles,each for $Rs. 1040$. He incurs $20 \%$ loss on the first and $10 \%$ loss on the second. Find out the overall percent loss.