Question 792950
Let the speed of the current be x km/hr.


So speed of the boat relative to the current while going upstream = (20-x) km/hr.
Speed of the boat relative to the current while going downstream = (20+x) km/hr.


Time for going upstream = 48/(20-x) hr.
Time for going downstream = 48/(20+x) hr.


Total time taken is: 48/(20-x) + 48/(20+x) = 5


Solve the above equation for x and get the answer.


Cheers!!!