Mixture and Alligation Questions

In what ratio should Assam tea at $\text{Rs. }40$ per kg and Darjeeling tea at $\text{Rs. }65$ per kg be mixed and sold at $\text{Rs. }60$ per kg to make an overall profit of $25\%$?

A businessman blends Assam tea costing $\text{Rs. }70$ per kg with Darjeeling tea costing $\text{Rs. }110$ per kg in the ratio $3:1$. What should be the selling price per kg of the new mixture to have a profit of $12\frac{1}{2}\%$ for him?

A milkman mixed water with $60\text{litres}$ of pure milk and sold the mixture at the cost price, thereby making a profit of $25\%$. Find the quantity of water in the mixture.