Answer:
Jeffry would have walked 1.5 miles or 1 1/2 miles
Explanation:
I'm assuming he will walk the same speed for the rest of the hour so if he walked at a rate of 3/4 a mile every half hour then in 1 hour he will have ran 6/4 miles or 1 2/4 miles which can be translated to 1.5 miles or reduced to 1 1/2 miles