A plane flies from Penthaven to Jackson and then back to Penthaven. When there is no wind, the round trip takes 6 hours and 24 minutes, but when there is a wind blowing from Penthaven to Jackson at 50 miles per hour, the trip takes 6 hours and 40 minutes. How many miles is the distance from Penthaven to Jackson? (Assume that the plane flies at a constant speed, and that the turnaround time is negligible.)
