$A$ pot contains $81$ $\text{litres}$ of pure milk. $\frac{1}{3}$ of the milk is replaced by the same amount of water. Again $\frac{1}{3}$ of the mixture is replaced by that amount of water. The ratio of the milk and water in the new mixture is?

$729 \, ml$ of a mixture contains milk and water in the ratio $7:2$. How much more water is to be added to get a new mixture containing milk and water in the ratio $7:3$? (in $ml$)

There are $65$ students in a class. $39$ rupees are distributed among them so that each boy gets $80$ Paise and each girl gets $30$ Paise. Find the number of boys and girls in that class.

In a mixture of $25\, L$,the ratio of acid to water is $4: 1$. Another $3\, L$ of water is added to the mixture. The ratio of acid to water in the new mixture is

$A$ sum of ₹ $390$ was divided among $450$ boys and girls. Each girl gets $50$ paise and each boy gets one rupee. How many girls are there among them?

$60 \ kg$ of a certain variety of rice at $Rs. 32$ per $kg$ is mixed with $48 \ kg$ of another variety of rice,and the mixture is sold at the average price of $Rs. 28$ per $kg$. If there is no profit or loss due to the new sale price,the price of the second variety of rice in $Rs.$ per $kg$ is: