Answer:
9 Km/h
Step-by-step explanation:
Walking 3 Km for 20 minutes from the definition of speed, it's distance covered per unit time. Here, the distance covered is expressed per unit hour.
Substituting 3.5 Km for distance and time for 20 minutes
To convert time into hours, we divide the minutes by 60 hence time=20/60=1/3 hours
Therefore, the speed is 9 Km/h