my answer would be 19.25 miles per hour. He has 1/3 left before it's an hour. He has already gone 2/3 of an hour so in 1/3 he will have gone for an hour. Half of 2/3 is one 1/3, so add half of the distance he has already gone to the original distance and you get 19.25. Probably not the right area for this question though.