Pure milk costs $16 / L$. After adding water,the milkman sells the mixture at $15 / L$ and thereby makes a profit of $25 \%$. In what respective ratio does he mix milk with water?

$A$ tub contains a mixture of two liquids $P$ and $Q$ in the ratio of $4:1$. When $10 \, L$ of the mixture is taken out and $10 \, L$ of liquid $Q$ is poured into the tub,the ratio becomes $2:3$. How many litres of liquid $P$ were contained in the tub initially?

Three containers whose volumes are in the ratio of $2:3:4$ are full of a mixture of spirit and water. In the $1^{st}$ container,the ratio of spirit to water is $4:1$,in the $2^{nd}$ container the ratio is $11:4$,and in the $3^{rd}$ container the ratio is $7:3$. All three mixtures are mixed in a big container. The ratio of spirit and water in the resultant mixture is:

$A$ merchant mixes three varieties of rice costing $Rs. 20$ per $kg$,$Rs. 24$ per $kg$,and $Rs. 30$ per $kg$ and sells the mixture at a profit of $20\%$ at $Rs. 30$ per $kg$. How many $kgs$ of the second variety will be in the mixture if $2$ $kgs$ of the third variety is there in the mixture?

$A$ can contains a mixture of two liquids $A$ and $B$ in the ratio $7:5$. When $9\,L$ of mixture is drained off and the can is filled with $B$,the ratio of $A$ and $B$ becomes $7:9$. How many litres of liquid $A$ was contained by the can initially?

Two vessels $A$ and $B$ contain milk and water mixed in the ratio $8: 5$ and $5: 2,$ respectively. The ratio in which these two mixtures should be mixed to get a new mixture containing $69 \frac{3}{13} \%$ milk is