If a commercial truck travels at 72 km/h (20 m/s), driver reaction time is 1.0 second, pneumatic brake lag is 0.4 seconds, and actual braking distance is 36 metres, what is the total stopping distance?

1. 64 metres (Reaction distance 20m + Brake lag distance 8m + Braking distance 36m = 64m)
2. 36 metres total
3. 100 metres total
4. 20 metres total