A, B and C can do a work in 6 days, 8 days and 12 days respectively. In how many days can all three of them working together, complete the work?	Select
A) 6 2/3 days.
B) 2 2/3 days.
C) 7 2/3 days.
D) 1 2/3 days.
E) 5 2/3 days.
B   2 2/3 days.   Work done by all three of them in one day = 1/6 + 1/8 + 1/12 = 3/8.   The number of days required = 8/3 = 2 2/3 days.
<result>B</result>
A, B and C can do a work in 6 days, 8 days and 12 days respectively. In how many days can all three of them working together, complete the work?