The part of this that does have a right answer

Most of this site is judgment with sources under it. This category is not. Dividing a restaurant bill, a group present or a weekend rental has an arithmetically correct answer, and the only reason it goes wrong is that nobody wants to be the person with the calculator out.

These tools are that person, so you do not have to be. They show the split line by line, including the awkward parts — who ordered the wine, who is on a different budget, who paid the deposit four months ago — in a form you can screenshot into the group chat and let stand on its own.