A can do a piece of work in 6 hours; B and C together can do it in 5 hours, while A and C together can do it in 3 hours. How long will B alone take to do it? Choose the correct choice:
A) 3 6/8 hours	B) 4 6/8 hours	C) 2 6/8 hours	D) 5 5/8 hours	E) none of the above
A's 1 hour's work = 1/6 ;   (B + C)'s 1 hour's work = 1/5 ;   (B + C)'s 1 hour's work = 1/3   (A + B + C)'s 1 hour's work = (1/6 + 1/5) = 11/30   B's 1 hour's work = (11/30 - 1/3) = 8/30   B alone will take 30/8 hours to do the work.   =3 6/8   3 6/8 hoursnswer = 3 6/8 hours
<result>A</result>
A can do a piece of work in 6 hours; B and C together can do it in 5 hours, while A and C together can do it in 3 hours. How long will B alone take to do it?