$100$ $litres$ 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 $litres$):

In what ratio should tea at ₹ $240$ per $kg$ be mixed with tea at ₹ $280$ per $kg$ so that on selling the mixture at ₹ $324$ per $kg$ there is a profit of $20 \%$?

There are two containers of equal capacity. The ratio of milk to water in the first container is $3:1$,and in the second container is $5:2$. If they are mixed together,then the ratio of milk to water in the mixture will be:

Vessels $A$ and $B$ contain mixtures of milk and water in the ratios $4:5$ and $5:1$ respectively. In what ratio should quantities of mixture be taken from $A$ and $B$ to form a mixture in which milk to water is in the ratio $5:4$?

$A$ mixture of $80$ litre of milk and water contains $10 \%$ water. How much water must be added to make $20 \%$ water in the new mixture? (in $litre$)

The ratio of alcohol and water in $40$ $litres$ of mixture is $5:3$. Then $8$ $litres$ of the mixture is removed and replaced with water. Now,the ratio of the alcohol and water in the resultant mixture is