The ratio of water and acid is 3 : 4.  If 39 liters of acid is mixed in the solution then the ratio changed to 2 : 3.  Find the ratio of water in initial and acid in final mixture.

2 : 3

                  Water    :      Acid

Initial    →      3        :       4      

Final      →      2        :      3

Here if we add only acid in initial mixture, then ratio of water should be same. Therefore,

                  Water    :      Acid

Initial    →      6        :       8      

Final      →      6       :       9

Required ratio = Intial water : Final acid = 6 : 9 = 2 : 3