There were three trains made of the cars with exactly the same number of passenger's seats. the first train had 418 seats, the second 456, and the third 494. how many cars were in each train, if it is known that each train had not more than 50 cars? 1 train=? 2 train=? 3 train=?

You apparently need to find the greatest common divisor of (418, 456, 494). You can start by looking at the differences between these numbers. They are
.. 456 -418 = 38
.. 494 -456 = 38
So, if 38 divides these numbers evenly, that is the number of seats in each car. (It does).

train 1 had 418/38 = 11 cars
train 2 had 456/38 = 12 cars
train 3 had 494/38 = 13 cars


The number of seats in each car could be a sub-multiple of 38, say 19. In that case, the number of cars in each train would be twice the number shown above. It is slightly unusual for a train car to have an odd number of seats, but is not unheard of.

Do you mean conversion factor?