Walk and Ride for Four
At the start Andy and Brianne rode the scooter and Clark and Delmar walked. After riding a certain distance Brianne got off the scooter and walked the rest of the way. Andy turned around and drove back to pick Clark up. Then the two of them drove until they caught up to Brianne. Clark got off and walked with Brianne to the concert. Andy turned around and drove back and picked up Delmar. Then the two of them drove to the concert.
If all four of them arrived at their destination at the same time how long was the trip ( in hours)?