THEM: i would like 2 balls and 1 book please.  YOU: you can have 1 ball and a book  THEM: no deal. i would like 1 book, 1 hat, and 1 ball then.  YOU: i need 2 hats and 1 ball  THEM: i need 2 balls and 1 book. or 1 book, 1 hat, 1 ball. otherwise, not enough for me to make a deal  YOU: ok. if i get 2 hats  THEM: ok, 2 hats for you. thanks.