$A$ dishonest trader professes to sell his article at cost price but he uses $900 \, g$ weight instead of $1 \, kg$. What is the percentage gain of the trader in this trade?

$A$ vessel of $160 \text{ litres}$ is filled with milk and water. $70 \%$ of milk and $30 \%$ of water is taken out of the vessel. After this task,it is found that the vessel is now filled by $55 \%$ of its original total quantity. What is the original quantity of milk and water in the vessel respectively?

Two liquids are mixed in the ratio of $3: 2$ and the mixture is sold at $Rs. 11$ per litre at a $10 \%$ profit. If the $1$st liquid costs $Rs. 2$ more per litre than the second,what is the cost per litre of the second liquid (in $.80$)? (in $Rs.$)

The ratio of milk and water in mixtures of four containers are $5:3$,$2:1$,$3:2$,and $7:4$,respectively. In which container is the quantity of milk,relative to water,the minimum?

In a mixture of $25\, L$,the ratio of acid to water is $4: 1$. Another $3\, L$ of water is added to the mixture. The ratio of acid to water in the new mixture is

$A$ can contains a mixture of two liquids $A$ and $B$ in the ratio $7:5$. When $9$ litres of mixture are drawn off and the can is filled with the same amount of liquid $B$,the ratio of $A$ and $B$ becomes $7:9$. How many litres of liquid $A$ was contained by the can initially?