A and B can do a piece of work in 8 days, B and C can do the same work in 12 days and A and C complete it in 8 days. In how many days A, B and C can complete the whole work,working together?

Efficiency of (A + B) = 12.5%
Efficiency of (B + C) = 8.33%
Efficiency of (C + A) = 12.5%
∴ Efficiency of [(A + B) + (B + C) + (C + A)] = 33.33%
∴ Efficiency of (A + B + C) = 16.66%
∴ No. of days Required by A, B and C together = 100/16.66 = 6 days