Shelia leaves on a long trip driving at a steady rate of 45 miles per hour. her sister allison leaves from the same location traveling to the same destination 2 hours later. she drives at a steady rate of 60 miles per hour. how long after shelia leaves home will allison catch up?

Let the time Shelia spend on the road be t. Thus, the time Allison spends on the road will be t-2 (assuming t is at least 2 hours).

Since distance is speed*time, we want the time when the distance Allison and Shelia to be the same:




Therefore, Allison will catch up the Shelia after Shelia is on the road for 8 hours (6 hours driving time for Allison).