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)

$A$ and $B$ are two alloys of gold and copper prepared by mixing metals in the ratio $7:2$ and $7:11$ respectively. If equal quantities of the alloys are melted to form a third alloy $C$,the ratio of gold and copper in $C$ will be

$A$ mixture contains spirit and water in the ratio $3:2$. If it contains $3 \ L$ more spirit than water,the quantity of spirit in the mixture is......$L$.

$300\, gm$ of salt solution has $40 \%$ salt in it. How much salt should be added to make it $50 \%$ in the solution? (in $gm$)

$A$ sum of ₹ $64$ is made up of $80$ coins which are either $100$ $paise$ or $50$ $paise$ coins. How many coins are of $50$ $paise$?

There are $3$ tubs which contain mixtures of milk and water in the ratios of $5:2, 4:3,$ and $3:1$ respectively. If the mixtures are poured into a single tub,find the ratio of milk to water.