$A$ 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?

$60 \ kg$ of a certain variety of rice at $Rs. 32$ per $kg$ is mixed with $48 \ kg$ of another variety of rice,and the mixture is sold at the average price of $Rs. 28$ per $kg$. If there is no profit or loss due to the new sale price,the price of the second variety of rice in $Rs.$ per $kg$ is:

In $50\, g$ alloy of gold and silver,the gold is $80\%$ by weight. How much gold should be mixed to this alloy,so that the weight of gold would become $95\%$? (in $g$)

Nine litres of water are drawn from a container full of water and it is then filled with milk. Nine litres of mixture are drawn and the container is again filled with milk. The ratio of the quantity of water now left in the container to that of the milk in it is $16:9$. How much liquid does the container hold? (in $litres$)

How many $kg$ of sugar costing ₹ $5.75$ per $kg$ should be mixed with $75 \, kg$ of cheaper sugar costing ₹ $4.50$ per $kg$,so that the mixture is worth ₹ $5.50$ per $kg$?

$A$ 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?