The cash difference between the selling prices of an article at a profit of $4 \%$ and $6 \%$ is $Rs. 3$. The ratio of the two selling prices is:

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)?

$A$ tradesman gives $4 \%$ discount on the marked price and gives $1$ book free for buying every $15$ books and thus gains $35 \%$. The marked price is increased above the cost price by (approx.) (in $\%$).

$A$ shopkeeper professes to sell his goods at cost price but uses a $930 \text{ g}$ weight instead of $1 \text{ kg}$ weight. What will be the profit percentage of the shopkeeper (in $\%$)?

$A$ fruit seller sells $\frac{3}{5}$ th part of fruit at a profit of $10 \%$ and the remaining at a loss of $5 \%$. If the total profit is $Rs. 1500$,then what is the total cost price of the fruit in $Rs.$?

If the cost price of $20$ articles is equal to the selling price of $15$ articles,find the profit percent?