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

Explanation

Suppose the can initially contains 7x and 5x of mixtures A and B respectively. Quantity of A in mixture left=7/(12)litres=Quantity of B in mixture left=5/(12)litres=[https://www.indiabix.com/_files/images/aptitude/1-sym-tfr.gif] [https://www.indiabix.com/_files/images/aptitude/1-sym-oparen-h1.gif] 7x-21 [https://www.indiabix.com/_files/images/aptitude/1-sym-cparen-h1.gif] 4/(4)=[https://www.indiabix.com/_files/images/aptitude/1-sym-imp.gif] 28x-21/(20x+21)=[https://www.indiabix.com/_files/images/aptitude/1-sym-imp.gif] 252x-189=140x+147 [https://www.indiabix.com/_files/images/aptitude/1-sym-imp.gif] 112x=336 [https://www.indiabix.com/_files/images/aptitude/1-sym-imp.gif] x=3. So, the can contained 21 litres of A.