Question : P and Q together complete a job in $4 \frac{2}{5}$ days. R and S complete the same job in $4 \frac{8}{9}$ days. If P, Q, R, and S work together, how many days do they need to complete the same job?

Question : 15 men can complete a work in 25 days and 25 women can complete the same work in 40 days. If all the 15 men and 25 women work together, in how many days will the work get completed?

Question : P, Q, and R can finish a work in 5 days, 10 days, and 15 days, respectively, working alone. P and Q work on the first day, P and R work on the second day, P and Q work on the third day and so on till the work is completed. In how many days the work will be completed?

Question : P, Q, and R can complete a piece of work in 9, 12, and 18 days, respectively. Working together, how much work can they complete in one day?

Question : P and Q together can do a job in 6 days. Q and R can finish the same job in $\frac{60}{7}$ days. P started the work and worked for 3 days. Q and R continued for 6 days. Then the difference in days in which R and P can complete the job is: