A and B can complete a work in 24 days and 36 days respectively. If they work together for 8 days, how much work is left?
Answer: B. 1/3 of the work
A's rate is 1/24 and B's rate is 1/36. Together, they complete 1/24 + 1/36 = 5/72 of the work per day. In 8 days, they complete 40/72 = 5/9 of the work, leaving 4/9.