Mixture and Alligation question bank (Quantitative Aptitude)

In a mixture of milk and water with a total volume of $60$ $L$,the ratio of milk to water is $7:5$. How much water must be added to make the ratio of milk to water equal $(1:1)$? (in $L$)

In a mixture of milk and water of volume $30$ $L$,the ratio of milk and water is $8:7$. How much water should be added to the mixture to make the ratio $4:5$? (in $L$)