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 option.
A) 8 hours  B) 10 hours  C) 12 hours  D) 24 hours  E) 25 hours
Explanation:   A's 1 hour's work =1/4   (B + C)'s 1 hour's work =1/3   (A + 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 IS 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?