Writing for Business – first come, first served or first-come-first-served?

Which is correct? A limited number of hard copies are available; you can pick them up on a _______________ basis. a. first-come-first-served b. first come, first served

Answer: a

Explanation: In this context, the phrase is an adjective modifying “basis” so we hyphenate.

As a standalone sentence, the phrase uses the other form: A limited number of hard copies are available. First come, first served.