A and B can do a work in 8 days, 13, 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 ?

(A + B + C)’s 1 day’s work = 1/6; (A + B)’s 1 day’s work = 1/8 (B + C)’s 1 day’s work = 1/12 (A + C)’s 1 day’s work = ( 2 X 1/6 ) – ( 1/8 + 1/12 ) = ( 1/3 – 5/24 ) = 3/24 = 1/8 So, A and C together will do the woirk in 8 days.