five construction workers can complete roofing in 6 day. how long will it take three construction workers to do the same job?

Question

Five construction can complete roofing an apartment in 6 days. How long will it take three construction workers to do the same job.

Answer 1

If you say that 1 construction worker working for 1 day accomplishes 1 unit of work, then 5 workers working for 6 days accomplish 30 units.  In order for 3 workers to accomplish 30 units, they'll have to work for 30/3 = 10 days.