THEM: ill take the book and balls you can have the hats.  YOU: i really need the book, you can have the rest  THEM: how about if you take the hats and 1 ball and i take a ball and the book the hats have no value to me.  YOU: the only thing that has value to me is the book  THEM: ok you can have the book ill take the rest.  YOU: deal, thanks.