Final answer:
To check the parking brake, you should put the parking brake on and drive at 20 km/h.
Step-by-step explanation:
To check the parking brake, you should put the parking brake on when driving at 20 km/h. This allows you to test if the parking brake is effectively holding the vehicle in place. Applying the parking brake at a higher speed may cause damage to the brake system and applying the parking brake at a lower speed may not provide an accurate assessment of the brake's functionality.