Answer:
Train going north = 50mph
Train going south = 100 mph
Explanation:
Let:
x = train traveling north
2x = train traveling south
D = Distance
S = Speed
T = Time
Let's use the formula for time, speed, and distance. Since we are looking for distance,
D = S * T
Both trains traveled 4 hours and in the end were 600 miles apart, this sets up our equation to be,
4x + 8x = 600
Now solve for s to find our speed.
x = 50 mph
This represents how fast the train going north was, since the train going south was going twice as much, then our second answer will be 100mph