A and B can do a piece of work in 12 and 15 days, respectively. They work together for 4 days, then B leaves. How many more days will A take to finish the work?
Q1. A and B can do a piece of work in 12 and 15 days, respectively. They work together for 4 days, then B leaves. How many more days will A take to finish the work?
Answer: 6 days
Explanation: The combined rate of work is 1/12 + 1/15 = (5 + 4)/60 = 9/60. Work done in 4 days = 4 * (9/60) = 3/5. Remaining work = 1 - 3/5 = 2/5.