Answer:
72 km/hr
Explanation:
First, convert from meters to kilometers. 20 meters is 0.02 kilometers.
Now that you have km/s, convert 0.02 km/s into km/h by multiplying it by the number of seconds in an hour. There are 3,600 seconds in an hour. Multiply 0.02 km/s by 3,600 secs/h to get 72km/h!