Final answer:
When parking on a slope without a curb, turn your wheels so your vehicle rolls away from traffic and into a ditch if brakes fail - away from the road if uphill and towards it if downhill.
Step-by-step explanation:
When parking headed uphill or downhill with no curb, the key is to ensure your car doesn't roll away. If you are parked on a slope, you should turn your wheels so that if your brakes fail, your vehicle will roll away from traffic or into the roadside ditch, not into the road.
For uphill parking, turn your steering wheel away from the road so the front wheels will roll into the ditch if the brakes give out. For downhill parking, do the opposite by turning your steering wheel towards the roadside, so the back wheels would block the car from moving into traffic.