84 km/h 105 km/h 180 km/h 210 km/h
I gave my students this multiple choice question: An airplane flies in a straight line between two cities that are separated by 840 kilometers. If it takes 4 hours for the airplane to make the trip, what is its average speed?

Only one answer is correct among these 4 choices:
- 84 km/h
- 105 km/h
- 180 km/h
- 210 km/h

Could you tell me which one is correct?

210 km/h