Explanation:
Let's call the time it took Pat and Rich to drive to the beach "x".
The time it took them to drive back was twice as long, so it took 2x hours.
The total time spent traveling was x + 2x = 3x hours.
Since they spent 9 hours traveling, 3x = 9 hours.
So, x = 9 hours / 3 = 3 hours.
This means it took Pat and Rich 3 hours to drive to the beach and 2 * 3 = 6 hours to drive back.