Question : A and B together can complete a given work in 10 days. C can complete the same work alone in 15 days. In how many days can they complete the work, if all three work together?

Question : $\mathrm{N}_1$ alone can do 20% of a piece of work in 6 days, $\mathrm{N}_2$ alone can do 20% of the same work in 4 days, and $\mathrm{N}_3$ alone can do 50% of the same work in 12 days. In how many days can they complete the work, if all of them work together?

Question : P alone can do a piece of work in 24 days. Q alone can do it in 30 days and R alone can do it in 20 days. In how many days they can complete it together?

Question : A piece of work can be completed by P and Q together in 24 days, and the same piece of work can be completed by R alone in 60 days. If P and R together can do the same work in 36 days, then find the time taken by Q to complete this piece of work alone.

Question : Rohan alone can do a work in 10 days and Mohan alone can do the same work in 15 days. In how many days will they together complete the same work?