Benny can do a piece of work in 24 days. Chethan and David can do the same work individually in 36 and 48 days, respectively. All of them begin the work together. However, Benny leaves the work 4 days before the completion of work and Chethan leaves the work 10 days before the completion of the work. David worked till the end and completed the work. Find the number of days in which the work was completed.

Ashok and Anil undertake to do a piece of work for ₹4,500. Ashok alone could do the work in the 8 days and Anil in 12 days. With the assistance of Amar, they finished the work in 4 days. What is the share of Amar?

A man, a woman and a boy can complete a job in 3, 5 and 15 days, respectively. How many boys must assist 1 man and 1 woman to complete the job in $\frac{1}{5}$ of a day?

If A, B and C can do a work in 6 days, 9 days and 11 days, respectively, then, working together, how many days will they take to do the work?