Final answer:
Turn the front wheels into the curb when parking downhill to ensure the car would roll into the curb and stop if the brakes fail.
Step-by-step explanation:
When you park downhill next to a curb, you should turn your front wheels into the curb. This way, if your car's brakes were to fail, the car would roll into the curb and stop, preventing it from rolling down the hill. It's an essential safety measure that keeps both your vehicle and others around you safe.