46.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?
A. 10 days B. 11 days
C. 15 days D. 20 days
Answer:
B's 1 day's work = (1/12 - 1/20)
= 2/60
= 1/30
Now, (A+B)'s 1 day's work (1/12 +1/60)
= 4/60
= 1/15.
So A and B together will complete the work in 15 days.
