A's 1 hour work = 1/4;
(B + C)'s 1 hour work = 1/2;
(A + C)'s 1 hour work = 1/2
(A + B + C)'s 1 hour work = (1/4 + 1/2) = 3/4
B's 1 hour work = (3/4 - 1/2) = 1/4
B alone will take 4 hours to do the work.
A can do a piece of work in 4 hours; B and C together can do it in 2 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?
Options:
[1] 2hours
[2] 3hours
[3] 4hours
[4] 5hours
[5] 6hours