A, B and C can complete a work in 20, 12 and 18 days respectively. In how many days A and B together can complete that work?

A’s rate = 1/20, B’s rate = 1/12 tasks/day. Combined rate = 1/20 + 1/12 = 3/60 + 5/60 = 8/60 = 2/15 tasks/day. Time = 1 ÷ (2/15) = 15/2 = 7.5 days. Note: 65/7 is likely a typo; correct answer is 15/2. Studying this highlights work rate problems, providing lessons on collaborative task planning.