Question

What is the avarage velocity of a car that travels 30 kilometers due west in 0.5 hours

Answer 1

Velocity is distance over time $v= \frac{d}{t}$. If it wants it in km/h you're good to go otherwise if its m/s you need to convert km to m by multiplying 30 by 1000 and t in hours to seconds by multiplying 0.5 by 3600.

Answer 2

Average velocity=distance/time
average v=s/t
averagev=0.3/30 min
 
so use your calculator 30min into seconds(30/60)
and divide your kilometre with your time(v=distance/time