A and B together do a work in 20 days.B and C together in 15 days and C and A in 12 days.so A,B and C together finish same work in how many days?  Choices.
A) 12  B) 15  C) 8  D) 10  E) 11
(A+B) work in 1 day= 1/20,(B+C) work in 1 days = 1/15.,(C+A) work in 1 days=1/12   (1) adding=2[A+B+C] in 1 day work = [1/20+1/15+1/12]=1/5   (A+B+C) work in 1 day= 1/10   So,all three together finish work in 10 days   Answer 10
<result>D</result>
A and B together do a work in 20 days.B and C together in 15 days and C and A in 12 days.so A,B and C together finish same work in how many days?