Joe 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 Monday there were 9 clients who did Plan A and 7 who did Plan B. On Tuesday there were 3 clients who did Plan A and 5 who did Plan B. Joe trained his Monday clients for a total of 12 hours and his Tuesday clients for a total of 6 hours. How long does each of the workout plans last?     length of each plan A workout?                 length of each plan B workout