My daughter and another senior went to tour a college campus yesterday.  The other girl was going by herself, and my daughter offered to go along.  I said I would pay for half of the trip.  Last night when they got home and I looked at all of the receipts I found three charges for fuel.  One the night before for roughly ten gallons ($40.00), one fill up for the return trip for roughly 8 gallons ($30.00), and a fill when they got home last night for another $20.00.  I then asked what lunch cost, and I added that to my half.

My thought process was as follows

The first $40 was of absolutely no benefit to my daughter.  I am liable for only the fuel used on the trip which added to fifteen gallons.  I figure that I am liable for approximately 7.5 gallons of fuel and the lunch tab. I wrote a check for $35.00. 

Next thing I know the phone is ringing and the other girls mother is reading me the riot act because I didn't pay for half of the first tank of gasoline from the night before.  After I argued my point I came to the conclusion that I was arguing a point that would never be understood by either of them.  I just agreed to pay the difference.  Was I out of line to begin with?  My obligation was to pay for half of the fuel on the trip. Not to pay for half of fuel to get ready for the trip.  Isn't that why rental cars are always full of fuel? All comments are appreciated.  I don't think I have ever been as mad over twenty dollars in all my life.