Efren leaves home at 9A.M. and walks 4 miles per hour. His brother, Gregory, leaves half an hour later and runs 8.5 miles per hour in the same direction as Efren. Predict the time at which gregoary will catch up to efrens.
Well, the first one gets a head start of 2 miles. The relative speed of the second one is 4.5 miles per hour (8.5-4), so you've got 2/4.5 hours. That is 120/4.5 minutes or 26 minutes 40 seconds. That is, 10:26:40
