A can do a work to 18 days, B in 27 days. They start together, but after 6 days A leaves. In how many more days will B finish the remaining work?

A's rate = 1/18, B's rate = 1/27. Together in 6 days: 6(1/18 + 1/27) = 6(3+2)/54 = 6×5/54 = 30/54 = 5/9. Remaining = 4/9. B alone: (4/9)/(1/27) = 4×27/9 = 12 days. Hmm, that gives 12. Let me recheck: remaining = 1 − 5/9 = 4/9. Days for B = (4/9) ÷ (1/27) = 12 days. The answer should be 12, correctIndex = 2.