Three glasses of equal volume contain acid mixed with water. The ratios of acid to water are $2:3$,$3:4$,and $4:5$ respectively. If the contents of these glasses are poured into a large vessel,what is the ratio of acid to water in the large vessel?

Nine litres of water are drawn from a container full of water and it is then filled with milk. Nine litres of mixture are drawn and the container is again filled with milk. The ratio of the quantity of water now left in the container to that of the milk in it is $16:9$. How much liquid does the container hold? (in $litres$)

The acid and water in two vessels $A$ and $B$ are in the ratio $4:3$ and $2:3$. In what ratio should the liquids in both the vessels be mixed to obtain a new mixture in vessel $C$ containing half acid and half water?

$A$ mixture of $40$ $litres$ of milk and water contains $10 \%$ water. How much water must be added to make $20 \%$ water in the new mixture? (in $Liters$)

$A$ mixture of milk and water measures $60 \, ltr$. It contains $20 \%$ water. How many litres of water should be added to it so that water may be $25 \% $ (in $ltr$)?

$100$ $litres$ of a mixture contains $20 \%$ water and the rest is milk. The amount of milk that must be added so that the resulting mixture contains $87.5 \%$ milk is (in $litres$):