A can do a piece of work in 8 hours; B and C together can do it in 12 hours, while A and C together can do it in 16 hours. How long will B alone take to do it?	Choose the correct choice from the following options:
A) 7 8/5 hours B) 5 9/8 hours C) 5 6/8 hours D) 6 6/7 hours E) none of the above
A's 1 hour's work = 1/8 ;   (B + C)'s 1 hour's work = 1/12 ;   (B + C)'s 1 hour's work = 1/16   (A + B + C)'s 1 hour's work = (1/8 + 1/12) = 5/24   B's 1 hour's work = (5/24 - 1/16) = 7/48   B alone will take 48/7 hours to do the work.   =6 6/7   Answer = 6 6/7 hours
<result>D</result>
A can do a piece of work in 8 hours; B and C together can do it in 12 hours, while A and C together can do it in 16 hours. How long will B alone take to do it?