In what ratio must a grocer mix two varieties of tea worth ₹ $60$ a $kg$ and ₹ $65$ a $kg$ so that by selling the mixture at ₹ $68.20$ a $kg$ he may gain $10 \%$?

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?

$A$ 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?

How much water should be added to $14$ litres of milk worth ₹ $5.40$ a litre so that the value of the mixture may be ₹ $4.20$ a litre? (in litres)

$300$ $gm$ of sugar solution contains $40 \%$ sugar. How much sugar (in $gm$) should be added to make the concentration $50 \%$ in the solution?

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: