If the ratio of the cost price and selling price of an article is $20: 21$,then what will be the profit percent (in $\%$)?

$A$ man buys $100 \, kg$ of sugar for $Rs. \, 2400$. He sold $1/4$th of the stock at a loss of $5 \%$. At what per cent profit should he sell the remaining stock so as to make an overall profit of $20 \%$ on the whole transaction? (in $\%$)

Two successive discounts of $4 \%$ on any item are equivalent to a single discount of $\%$

Anil bought an item with $12 \frac{1}{2} \%$ discount on the labelled price. He sold the item with $17 \frac{1}{2} \%$ profit on the labelled price. What was his percent profit on the price he bought?

If $11$ mangoes are bought for $Rs. 10$ and sold at $10$ for $Rs. 11$,what is the gain or loss percentage (in $\%$)?

Meenal purchased a car for $Rs. 2,50,000$ and sold it for $Rs. 3,48,000$. What is the percent profit she made on the car?