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 :
4 days
6 days
8 days
12 days
Explanation:
$\left(A + B + C\right)$s 1 days work =$ \dfrac{1}{6} $;
$\left(A + B\right)$s 1 days work =$ \dfrac{1}{8} $;
$\left(B + C\right)$s 1 days work =$ \dfrac{1}{12} $.
$\left(A + C\right)$s 1 days work =$ \left(2 \times \dfrac{1}{6} \right) $-$ \left(\dfrac{1}{8} +\dfrac{1}{12} \right) $
=$ \left(\dfrac{1}{3} -\dfrac{5}{24} \right) $
=$\dfrac{3}{24}$
=$\dfrac{1}{8}$.
So, A and C together will do the work in 8 days.