Are you ready for a brain twister? murphy can row at 5 kmph in still water. if the velocity of current is 1 kmph and it takes him 1 hour to row to a place and come back, how far is the place?

2.4km

In this case, Murphy is rowing to a place and come back so he was going 2x of the place distance. That means when he goes to the place the current velocity is helping him(5+1 kmph) and when he comes back the current velocity is slowing him(5-1kmph).
To calculate the place distance, the calculation would be:
X/6kmph + X/4kmph= 1 hour
X/6kmph + 1.5X/6kmph= 1 hour
2.5X/6kmph= 1hour
2.5X= 1 hour x 6km/ hour
X= 6km/2.5
X= 2.4km