$A$ man bought apples at the rate of $6$ for $Rs. 20$ and sold them at $4$ for $Rs. 16$. His estimated profit $\%$ is

$A$ rice trader buys $8$ quintals of rice for $Rs. 3,600$. $10\%$ of the rice is lost in transportation. At what rate should he sell the remaining rice to earn a $15\%$ profit in $Rs.$ per quintal?

The percentage profit earned by selling an article for $Rs. 1920$ is equal to the percentage loss incurred by selling the same article for $Rs. 1280$. At what price should the article be sold to make $25 \%$ profit? (in $Rs.$)

$A$ dealer marks his goods $30\%$ above his cost price and then allows a $15\%$ discount on it. What is the cost price of an article on which he gains $₹84$?

$A$ shopkeeper allows a discount of $10 \%$ on the marked price of a camera. The marked price of the camera,which costs him $₹ 600$,to make a profit of $20 \%$ should be (in $₹$):

$A$ person earns $15 \%$ on an investment but loses $10 \%$ on another investment. If the ratio of the two investments is $3:5$,what is the gain or loss percentage on the two investments taken together (in $\%$)?