Amar rows to a place 80 km distance and back in total of 36 hours. He finds that he can row 10 km with the stream in same time as 8 km against the stream. What is the speed of boat in still water?
1
5 km/hr
2
5.5 km/hr
3
4 km/hr
4
4.5 km/hr
5
6.5 km/hr