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.

$A$ man buys two cows for ₹$1350$ and sells one,so as to lose $6 \%,$ and the other so as to gain $7.5 \%$ and on the whole he neither gains nor loses. What does each cow cost?

There are $65$ students in a class. $39$ rupees are distributed among them so that each boy gets $80$ Paise and each girl gets $30$ Paise. Find the number of boys and girls in that class.

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 $5:4$?

$8$ litres are drawn from a cask full of wine and is then filled with water. This operation is performed three more times. The ratio of the quantity of wine now left in the cask to that of the water is $16$:$65$. How much wine did the cask hold originally? (in litres)

If $5 \ kg$ of potato costing $Rs. 5$ per $kg$ and $3 \ kg$ of potato costing $Rs. 4$ per $kg$ are mixed,find the average cost of the mixture per $kg$?