A motor boat takes 2h to travel a distance of 9 km down the current and it takes 6h to travel against the current. The speed of the boat in still water and that of the current (in km/h) respectively are
1
3 km/h and 1.5 km/h
2
3 km/h and 1 km/h
3
3 km/h and 2.5 km/h
4
3 km/h and 2 km/h