Deshaun 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 7 clients who did plan a and 9 who did plan b. on tuesday there were 5 clients who did plan a and 3 who did plan b. deshaun 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?