Answer:
36 miles per hour
Explanation:
Since the man has covered 2/5 of the tunnel, he still has 3/5 of the tunnel to go. If he runs ahead, the time it takes for him to cover 3/5 of the tunnel is the same time it takes for the train to cover the whole tunnel (5/5)
In order words, his speed is 3/5 of the train speed.
So the rate, in miles per hour that he is running, is:
60 * 3/5 = 36 miles per hour