A movie stunt double is supposed to run across the top of a train (in the opposite direction that the train is moving) and just barely jump off before reaching a tunnel, but after running the entire length of the train (starting from the front). If the train is moving at 50 km/hr, is 3 km long and the tunnel is 40 km away from the end (where the stunt double is going to jump from), how fast (in km/hr) will the stunt double need to run