Annabelle is taking the polar express all the way to the north pole! the polar express is 100 meters longs and it takes 30 seconds to cross santa's 400m ice bridge. what speed is the train going at?

So first to find the speed of the train you must first figure out what the “useless” info is. In this case it would be how long to train is. Then you would take the distance of the bridge (400 meters) and divide it by the time it takes you to cross the bridge (30 seconds) to get your answer.