$120$ litres mixture of milk and water contains $40\%$ milk. How much milk (in litres) must be added so that milk becomes $50\%$:

In a mixture, milk and water are in ratio of $2 : 3$. Some milk is added to the mixture because of which ratio of milk and water becomes $2 : 1$. How much milk was added as a percentage of initial mixture?

In two vessels$A$ and $B,$ the milk and water are in the ratio of $5:2$ and $4:5$ respectively. The ratio in which these are mixed to obtain new mixture which contains milk and water in the ratio $3:2$ is:

In what ratio, sugar costing $₹60$ per kg be mixed with sugar costing $₹42$ per kg such that by selling the mixture at $₹56$ per kg there is a gain of $12\%$?