Provide your best answer for the following math problem. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The problem is: 14 men can complete a piece of work in 25 days . in how many days can 20 men complete that piece of work ?
17.5 days
12.5 days.