What quantity can you calculate if you know that a car travels 30 km inn 20 minutes?

Knowing the distance covered and the time to cover the distance,

you can calculate the car's average speed during that time.

Average speed = (distance covered) / (time to cover the distance)

Average speed = (30 km) / (20 minutes) = 1.5 km/minute.

Note: You do NOT have enough information to calculate velocity.