Recall your d = rt, distance = rate * time
so... one train goes west and the goes the opposite way... alrite... so... notice, by the time 338 miles have been covered by both, it will have been "t" hours, and whatever "t" is, is the same amount of time the westbound train has been running as well as the eastbound train has been running.
now, let's say, since by "t" hours they've covered 338 altogether, so, if the westbound train has covered say "d" miles, then the eastbound train would have covered the slack from 338 and d, that is, "338 - d".

so, 2hours and 36 minutes.
Any kind of Triangle must have 180 degree of angle in total if it is not, then it is not a Triangle.
In short, Your Answer would be Zero
Hope this helps!
Pretty sure it’s 5x^2 - 2x