Answer:
100 miles
Step-by-step explanation;
The man spent a total of 30 minutes travelling ( because he travelled from 5:30 t0 6:00 PM ). Now since we know that the man travelled at a speed of 100 miles per hour and that 30 minutes is half of an hour (30 min = 1/2 hr) then we conclude that the distance he travelled is
100 miles / 2 = 50 miles.
Or more formally we can do
Hence, the distance travelled by the man is 50 miles.