A rowing team rows a boat and covers a distance of 18 km in 6 hours while going upstream. When they go downstream, they cover a distance of 30 km in 5 hours. Find the speed of the boat in still water?

• ক 3.5 km/h
• খ 4.5 km/h ✅ সঠিক উত্তর
• গ 5.5 km/h
• ঘ 2.5 km/h