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

On an order of $5$ dozen boxes of a consumer product,a retailer receives an extra dozen free. This is equivalent to allowing him a discount of........$\%$

$A$ man sold two cows at $Rs. 1995$ each. On one he lost $10\%$ and on the other he gained $10\%$. What is his gain or loss percent (in $\%$)?

$A$ shopkeeper bought $30\, Kg$ of wheat at the rate of $Rs.\, 45$ per $Kg$. He sold $40\%$ of the total quantity at the rate of $Rs.\, 50$ per $Kg$. Approximately,at what price per $Kg$ should he sell the remaining quantity to make $25\%$ overall profit? (in $Rs.$)

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

Anil started a business with an investment of $Rs. 25,000$. After $3$ months,Vishal joined his business with a capital of $Rs. 30,000$. At the end of the year,they made a profit of $Rs. 19,000$. What will be Anil's share in the profit? (in $Rs.$)