Chang the trainer has two solo workout plans that he offers his clients: Plan A and Plan B. Each client does either one or the other (not both). On Friday there were 5
clients who did Plan A and 3
who did Plan B. On Saturday there were 7
clients who did Plan A and 9
who did Plan B. Chang trained his Friday clients for a total of 6
hours and his Saturday clients for a total of 12
hours. How long does each of the workout plans last?