Two trains leave the station at the same time, one heading east and the other west. the eastbound train travels at miles 90 per hour. the westbound train travels at miles 80 per hour. how long will it take for the two trains to be 204 miles apart?

So the eastbound train travels at 90 miles per hour in the complete opposite direction to the westbound equivalent, which travels at 80 miles per hour. Therefore, per hour, they get 170 miles away from each other. Since we are working out how long it would take for them to be 204 miles apart:

204 / 170 = 1.2 Hours, or 1 hour and 12 minutes.

Hope I helped!