First of all we must use the same unit measure for all data, otherwise it wouldn't make sense to compare meters and kilometers.
Since one kilometer is the same as 1000 meters, we have that 920000 meters are 920 kilometers.
Now, the train travels at 230 kilometers per hour. It means that it travels 230 kilometers with each passing hour
So, after 1 hour, the train travels 230 km. After two hours, the train travels 2x230 = 460km, and so on
In general, the distance traveled after k hours is .
We want that distance to be 920, so the equation is
So, the train travels 920 kilometers (i.e. 920000 meters) in 4 hours.