I have come across a situation that I'm not entirely sure how to handle and am curious if there are any norms in the United States for it.
I teach in my university's foreign language department. A colleague in another department approached me to see if I could assist in translating an article for a book that he was working on. The article is in the language that I specialize in and also very closely related to my research area.
If it were just a paragraph, I would of course do it without question. However, given its length (about 13k words), I'm not sure how to approach. He has offered to pay, but is it normal to charge the same amount as I would were it a private business? Or is it expected to offer a reduced rate in the name of "service"?