Question

If a and b can do a piece of work in 15 days, b and c can do in 12 days , c and a can do in 20 days. how many days are recquired if a,b,c works together?

Answer 1

1. Given a+b=1/15----------->1;
2. B+C=1/12----------->2;
3. C+A=1/20--------->3
4. On adding 1,2,3 we get
5. 2(A+b+c)=(1/15)+(1/12)+(1/20)
6. from this we get A+B+C=1/10
7. hence these 3 members can complete work in 10 days