The speed of a boat downstream is 15 km/hr and the speed of the stream is 1.5 km/hr. The speed of the boat upstream is ?

• ক 12 km/hr ✅ সঠিক উত্তর
• খ 13.5 km/hr
• গ 8.25 km/hr
• ঘ 16.5 km/hr