Two cities A and B are connected by a 200km long train line. A train leaves A for B at 20 km / h at the same time as another train leaves B for A at 5 km / h. In the same moment a fly leaves from A to B following the train line. The fly flies at 40 km / h until it collides with train B. At that moment it returns instantly and follows the train line until it collides with train A. At that moment it returns instantly and follows the line of the train. train until it collides with train B. The fly continues this process, traveling ever smaller distances until the two trains meet. (It is an ideal problem and the fly does not get squashed by the trains). What is the total distance traveled by the fly?

Two cities A and B are connected by a 200km long train line. A train leaves A for B at 20 km / h at the same time as another train leaves B for A at 5 km / h. In the same
moment a fly leaves from A to B following the train line. The fly flies at 40 km / h until it collides with train B. At that moment it returns instantly and follows the train line until it collides with train A. At that moment it returns instantly and follows the line of the train. train until it collides with train B. The fly continues this process, traveling ever smaller distances until the two trains meet. (It is an ideal problem and the fly does not get squashed by the trains).
What is the total distance traveled by the fly?