Two discounts of $40 \%$ and $20 \%$ equal to a single discount of $\%$?

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.

When a producer allows $36 \%$ concession on the retail price of his product, he earns a profit of $8.8 \% .$ What would be his profit percent if the commission is reduced by $24 \% ?$

A shopkeeper purchased $70$ $kg$ of potatoes for $Rs.\, 420$ and sold the whole lot at the rate of $Rs.\, 6.5$ per $kg.$ What will be his gain percent?

A fruit seller bought $240$ bananas at the rate of $Rs.\, 48$ per dozen. He sells half of them at the rate of $Rs.\,5$ per banana, $\frac{1}{6}$ th of the remaining are found to be rotten. The price per banana at which he has to sell the remaining bananas to get a profit of $25 \%$ on his entire investment is (in $Rs.$)

A fruit vendor buys $10$ bananas for $Rs.\, 14$ and sells them at $12$ for $Rs.\,15$. Find his percentage gain or loss.