A can do a piece of work in 4 hours; B and C together can do it in 3 hours, while A and C together can do it in 2 hours. How long will B alone take to do it?	Choose the correct choice:	A) 8 hours	B) 10 hours	C) 12 hours	D) 24 hours	E) none of the above
A's 1 hour's work = 1/4 ;   (B + C)'s 1 hour's work = 1/3 ;   (B + C)'s 1 hour's work = 1/2   (A + B + C)'s 1 hour's work = (1/4 + 1/3) = 7/12   B's 1 hour's work = (7/12 - 1/2) = 1/12   B alone will take 12 hours to do the work.   Answer = 12 hours
<result>C</result>
A can do a piece of work in 4 hours; B and C together can do it in 3 hours, while A and C together can do it in 2 hours. How long will B alone take to do it?