Because the two trains are traveling opposite directions, we can add there two speeds to see how many miles per hour they are traveling apart. This is equal to 95 + 115 = 200.
So, the trains are moving 200 miles per hour apart from each other.
Now, we divide 336 by 200 to see how long it will take. 336/200 = 1.68, so it will take the two trains 1.68 hours to travel 336 miles apart.