It's a lot of work getting pretzels for Bob, but it's worth it, since he pays us $2.00, and takes care of the actual cost of the pretzels.
How many did you bring me this time?
Not tellin'. You owe me $17.00.
If I owe her $17, 2 are for her, and 3 are for each pretzel bag, then 17-2=15, so she got 5 bags. That might not be enough. -But at least I know how many there are, so I know to ration them with only two bags per day.