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?
Options
A) 22  B) 88  C) 15  D) 66  E) 81
B's 1 day work = (1/12 - 1/20) = 1/30   Now, (A + B)'s 1 day work = (1/20 + 1/60) = 1/15   So, A and B together will complete the work in 15 days.   Answer: 15
<result>C</result>
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?