Consider the question. A can do a piece of work in 6 hours; B and C together can do it in 4 hours, which A and C together can do it in 3 hours. How long will B alone take to do it?
Options:
(A) 8hours
(B) 6hours
(C) 14hours
(D) 12hours
(E) 5hours
What is the step-by-step reasoning process to arrive at the answer: (D)?
A's 1 hour work = 1/6;
(B + C)'s 1 hour work = 1/4;
(A + C)'s 1 hour work = 1/3
(A + B + C)'s 1 hour work = (1/4 + 1/6) = 5/12
B's 1 hour work = (5/12 - 1/3) = 1/12
B alone will take 12 hours to do the work.