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?

15 men complete a work in 10 days. 15 women complete the same work in 12 days. If all these men and women work together, then the number of days required to complete that work is:

Ramesh alone can complete a work in 24 days. Ramesh and Somesh can complete it in 8 days. How long will Somesh alone take to complete the work?