If we could clone a single person from the past, Solomon is someone who would get strong consideration. The man had useful negotiating skills, not to mention a magic ring. Still, when thorny situations involving competing interests come up sometimes it’s not all that hard to channel him. Let’s pick an apropos topic at random and see if that is true. (The topic wheel is spun and settles on the following topic – authors who unexpectedly bring their own books to events covered by a bookseller)

I think that topic will work well. It is a clear case of competing interests. Both the bookseller and the author want to make the standard industry discount of 40% at a minimum at events. Since the laws of economics stipulate that discount is finite, that outcome is not possible.
You’ll note that I used the word unexpectedly in my description. Best practice always involves working out the details of author-provided books at events in advance, even though it is not a happy subject. Nonetheless, sometimes this is not an option. For example, I was covering an evening school event recently which involved a two-day author visit. Our only role was to sell books at the evening event. The selection of titles was done in close collaboration with the school’s event coordinator.  It came to light, however, that the author had brought a supply of one of her out-of-print titles. She had featured that title prominently during her in-class presentation and, in the hurly burly of getting my table set up, I was given a stack of the book to sell and had no opportunity to discuss terms.
Let’s look at things from both perspectives. From the author’s perspective she has purchased the book in bulk from her publisher and has the very reasonable expectation of making a profit on the sale of the book. She may feel that there is no cost for the bookseller to sell that book, and that it should be done as a service, with all the money received for the book given to her.
The bookseller’s perspective is very different. The expense of staffing the event is considerable for a bookstore. Most importantly, attendees of school events are only going to buy a finite number of books. Titles featured during an in-class presentation are a big driver of sales. Thus the sale of the featured, author-provided title comes at the direct expense of the bookseller-provided copies of the author’s books. The upshot of that is fewer sales, less profit, more returns, and therefore greater expenses for the bookstore. It represents a very real loss of revenue at the event. These same negatives apply to the publisher’s return on the event. Though this situation is clear to booksellers, I am describing it because I am all too aware, from recent experience, that it is not uniformly obvious to authors.
Solomon’s wisdom on this topic was pretty obvious. When he suggested dividing an infant in half, the real mother’s response was properly one of horror. Discount percent, however, can be divided equally without mortal harm to either the bookseller or the author. Each party receiving 20% of the sale is clearly the fair and best practice here because both the bookseller and the author have perfectly legitimate interests in making a return on their independent investments of time and resources.