1. Person A and Person B are standing by the railway waiting for a train. It is known that the train is moving at a constant speed. At a certain moment, when the front of the train passes them, A starts walking in the same direction as the train at a constant speed, while B walks in the opposite direction at the same speed. When the rear of the train passes either of them, that person stops moving. In the end, A walked 45 meters, and B walked 30 meters. Find the total length of the train.