A and B together can complete a work in 12 days,. A alone can complete it in 20 days. If B does the work only for half a day daily, then in how many days A and B together will complete the work?
Q1. A and B together can complete a work in 12 days,. A alone can complete it in 20 days. If B does the work only for half a day daily, then in how many days A and B together will complete the work?
Answer: 15 days
Explanation: B works only half a day, so B's effective rate = 1/60 per day; combined rate = 1/20 + 1/60 = 4/60 = 1/15, giving 15 days.