IBPS RRBs Officer Scale I and II 12 Se 2015 Paper

The speed of the boat in still water is 24 kmph and the speed of the stream is 4km/h. The time taken by the boat to travel from A to B downstream is 36 minutes less than the time taken by the same boat to travel from B to C upstream. If the distance between A and B is 4 km more than the distance between B and C, what is the distance between A and B ?