Answer:
10.6 km/h
Step-by-step explanation:
avg. speed in km/h literally tells us how much distance (in km) the cyclist travels in an hour. An hour happens to be double that of 30 minutes, so the distance will be double of 5.3km. The distance over an hour is 10.6km, so the speed is 10.6km/h.
Alternatively, you can simply divide distance by time:
5.3km / 30min = 5.3km / (1h / 2) = 5.3km * 2 / 1h = 10.6km/h
