A and B can do a work in 8 days, B and C can do the same work in 12 days. A, B and C together can finish it in 6 days. A and C together will do it in
Solution
Assume total work to be 24 units (common multiple of 8, 12 and 6).
A and B can do 24 units of work in 8 days. (A+B)'s one day work = 3 units
B and C can do 24 units of work in 12 days. (B+C)'s one day work = 2 units
A, B and C can do 24 units of work in 6 days. (A+B+C)'s one day work = 4 units
Multiply third equation by 2 and subtract first two equations,
2(A+B+C) - (A+B) - (B+C) = 2*4 - 3 - 2
(A+C)'s one day work = 3 units
A and C can do 24 units of work in 8 days.
The correct option is A.