Answer:
60 mph
Step-by-step explanation:
We calculate the combined distance travelled by the two trains in two hours.
As they were 500 miles apart at first, and 300 miles apart after, they have travelled 200 miles together.
I think the question means "one train travels 20 mph faster than the other".
Say the faster train has speed x mph. Then the slower has speed x - 20 mph.
Now, the combined distance travelled in 2 hrs is 2 * (x + x - 20) = 200
2x - 20 = 100
2x = 120
x = 60 mph
