A and B together can finish a bit of work in 12 days, B and C can do it in 20 days and C and A do it 15 days. A, B and C together can finish it in-

Question: A and B together can finish a bit of work in 12 days, B and C can do it in 20 days and C and A do it 15 days. A, B and C together can finish it in-

Solution:
(A + B) 1days works =1/12,
(B + C) 1days work =1/20,
(C + A) 1 days work=1/15.

2(A + B + C) 1days work = (1/12 + 1/20 + 1/15)
= (5 + 3 + 4)/60
=12/60
=1/5.

⇒ (A + B + C) 1 days works=1/10.
∴A, B and C together can do it in 10 days