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 $\%$)?

$A$ person sells taperecorders at $Rs. 1134$ each after giving a discount of $19 \%$ on the marked price. Had he not given the discount,he would have earned a profit of $40 \%$ on the cost price. The cost price of each taperecorder is (in $Rs.$)

$A$ man had a certain amount with him. He spent $20\%$ of that to buy an article and $5\%$ of the remaining on transport. Then he gifted $Rs. 120$. If he is left with $Rs. 1,400$,the amount he spent on transport is (in $Rs.$)

$A$ trader marks his goods $40 \%$ above the cost price and allows a discount of $25 \%$. The profit he makes,is in $\%$:

$A$ cycle dealer offers a discount of $10 \%$ and still makes a profit of $26 \%$. What does he pay for a cycle whose marked price is $₹ 840$? (in $₹$)

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)?