Time and Work - General Questions

A and B together can complete a work in 8 days. A alone can complete it in 10 days. In how many days can B alone complete the work?

A can finish a work in 14 days and B in 14 days. They work together for 5 days and then A leaves. In how many more days will B finish the remaining work?

A is twice as efficient as B. Together they finish a job in 12 days. How long would A take to do it alone?

A can do a piece of work in 9 days and B can do it in 21 days. In how many days will they finish it working together?

A can finish a work in 13 days and B in 26 days. They work together for 2 days and then A leaves. In how many more days will B finish the remaining work?