Question

A+b can do a piece of work in 10 days, b+c can do it in 20 days and a+b+c can do it in 30/11 days. in how many days can c+a complete the work?

Answer 1

A+B one day work=1/10

B+C one day work=1/20

A+B+C one day work=11/30

c+a complete the work=11/30-(1/10/1/20)

=11/30-3/20=13/60