$A$ man buys $2$ cows for $Rs. 2700$ and sells one at a loss of $6\%$ and the other at a gain of $7.5\%$. On the whole,he neither gained nor lost. What is the cost price of the $2^{nd}$ cow?

$A$ mixture contains wine and water in the ratio $3:2$ and another mixture contains them in the ratio $4:5$. How many litres of the latter must be mixed with $3 \, L$ of the former so that the resulting mixture may contain equal quantities of the wine and water? (in $L$)

$49 \ kg$ of blended tea contains Assam and Darjeeling tea in the ratio $5:2$. The quantity of Darjeeling tea to be added to the mixture to make the ratio of Assam to Darjeeling tea $2:1$ is..........$kg$.

If $2 \, kg$ of metal,of which $\frac{1}{3}$ is zinc and the rest is copper,is mixed with $3 \, kg$ of metal,of which $\frac{1}{4}$ is zinc and the rest is copper,what is the ratio of zinc to copper in the mixture?

$A$ dishonest milkman professes to sell his milk at cost price but he mixes it with water and thereby gains $25 \%$. The percentage of water in the mixture is?

In what ratio must sugar at $Rs. 2$ per $kg$ be mixed with sugar at $Rs. 3.50$ per $kg$ so that the mixture is worth $Rs. 2.50$ per $kg$?