Ugh! Why can't English be like Spanish and have some sort of Real Academia Inglesa? In any case, the lack of proper hyphenating rules leads me here.
I'm translating a brochure that talks about mail order drugs. In several instances it mentions "Suplido de 30 días" Which I've translated as "30-day supply". I'm almost possitive that there is a hyphen in 30-day. But I could use some feed back on this.