Answer:
78.6km/h
Step-by-step explanation:
Speed=distance÷time
distance=21km
time=16 minutes(convert into hour by dividing it with 60)
=16÷60=0.267
Speed=21÷0.267=78.65km/h
[tex]speed = \frac{distance }{time} [/tex]
[tex]speed = \frac{21}{0.267} = 78.6km(h[/tex]