The two trains would take 2.4 hours to be 336 miles apart
Solution:
Two trains leave the station at the same time, one heading west and the other east
So, they are moving in opposite direction
Speed of westbound train = 80 miles per hour
Speed of east bound train = 60 miles per hour
To find: time taken for two trains to be 336 miles apart
Distance between them = 336 miles
The speeds are added when going in opposite directions
Therefore,
speed = 80 + 60 = 140 miles per hour
Speed is given by formula:

Rearrange the formula to find time

Thus the two trains would take 2.4 hours to be 336 miles apart