To process a batch of parts, it takes 12 hours for Party A to do it alone, 8 hours for Party B to do it alone, and how many parts are left after Party A and Party B do it together for one hour? We need to do it today

To process a batch of parts, it takes 12 hours for Party A to do it alone, 8 hours for Party B to do it alone, and how many parts are left after Party A and Party B do it together for one hour? We need to do it today

1-(1/12+1/8)*1=1-5/24=19/24