Mahesh purchased $25\, kg$ of rice at $Rs. 32$ per $kg$ and $15\, kg$ of rice at $Rs. 36$ per $kg.$ He mixed the two varieties of rice and sold it at $Rs. 40.20$ per $kg.$ What is the percent profit earned (in $\%$)?

$A$ man sells a scooter to his friend at $10\%$ loss. If the friend sells it for $₹ 54000$ and gains $20\%$,find out the original cost price of the scooter. (in $₹$)

$A$ sold a pen to $B$ at a profit of $20\%,$ $B$ sold the same pen to $C$ for $Rs.\,75$ thereby making a profit of $25 \% .$ Find the price at which $A$ bought the pen? (in $Rs.$)

$A$ 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?

By selling an article for $Rs. 21$,a man incurs a loss such that the percentage loss is equal to the cost price. The cost price of the article is (in $Rs.$):

Sardar Singh bought $200$ dozen oranges at $Rs. 10$ a dozen. He spent $₹500$ on transportation. He sold them at $Rs. 1$ each. What was his profit or loss percent?