8 men can do a piece of work in 9 days.
Question:

8 men can do a piece of work in 9 days. In how many days will 6 men do it?

Solution:

It is given that 8 men can complete a job in 9 days.

$\therefore$ Time taken by 1 man to complete the same job $=(8 \times 9)=72$ days

$\therefore$ Time taken by 6 men to complete the same job $=\frac{72}{6}=12$ days