$A$ shopkeeper sells a badminton racket,whose marked price is $Rs. 30$,at a discount of $15\%$ and gives a shuttlecock costing $Rs. 1.50$ free with each racket. Even then,he makes a profit of $20\%$. His cost price per racket is (in $Rs$):

If the selling price is tripled and the cost price is doubled,the profit would become $65 \%$. What is the present profit (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)?

The marked price of a watch was $Rs. 720$. $A$ man bought the same for $Rs. 550.80$ after getting two successive discounts,the first being $10 \%$. The second discount rate is.......$\%$

$A$ dairyman pays $Rs. 6.40$ per litre of milk. He adds water and sells the mixture at $Rs. 8$ per litre,thereby making $37.5\%$ profit. The proportion of water to milk received by the customers is

Nisha bought a number of oranges at $2$ for a rupee and an equal number at $3$ for a rupee. To make a profit of $20 \%$ she should sell a dozen for (in $Rs.$)