To complete a work, A and B take 30 days, B and C take 24 days, and C and A takes 20 days. They all start together and work for 5 days after which B and C leave. How many more days will A take to finish the remaining work?

Given: A+B=30 days, B+C=24 days, C+A=20 days. Combined rate (A+B+C)/2 = (1/30+1/24+1/20)/2 = (4+5+6)/120 × 1/2 = 15/240 = 1/16, so all three complete work in 16 days together. In 5 days they complete 5/16 of work. Remaining 11/16 done by A alone at rate (1/16 - 1/24) = (3-2)/48 = 1/48. Time = (11/16)/(1/48) = 11×3 = 33 days. Option C is correct.