Question : John can do a piece of work alone in 20 days, while Ravi can do the same piece of work alone in 28 days. In how many days can the duo complete the same work if they work together?

Question : A can do $\frac{4}{5}$th of a work in 20 days and B can do $\frac{3}{4}$th of the same work in 15 days. They work together for 10 days. C alone completes the remaining work in 1 day. B and C together can complete $\frac{3}{4}$th of the same work in:

Question : A can do a certain piece of work in 2.4 times the number of days in which B and C together can do it. If A and B together can do the same piece of work in 27 days and C alone can do it in 75 days, then how many days will B take to do this piece of work alone?

Question : A can do a piece of work in 10 days, while A and B together can complete it in $2 \frac{1}{2}$ days. How long will B alone take to complete the work?

Question : A can do $\frac{2}{5}$ of a work in 12 days while B can do $66 \frac{2}{3}\%$ of the same work in 16 days. They work together for 10 days. B alone will complete the remaining work in: