Andrea and Beth are dining at a fine restaurant. There is a bottle of 2009 Grgich Hills Chardonnay on the menu and the price is $100. To keep things simple, albeit unrealistic, assume the restaurant only sells whole bottles and this is the only wine they carry.

• Andrea would be willing to pay $110 to drink the whole bottle.
• Andrea would be willing to pay $90 to drink half the bottle.
• Beth would be willing to pay $80 to drink the whole bottle.
• Beth would be willing to pay $50 to drink half the bottle.

They would like to share a bottle if it makes sense to do so (and if they can agree on how to divide the costs). To see if it makes sense, what is the pie?