Where's My $10?

Friday night was pretty busy as usual.  I had good deliveries that all tipped.  Mostly $4 and $5 at each.

One customer ended up giving me a $5 tip, but she tried to rip me off first.  Mostly because she didn't understand math and not because she was trying to rip me off.  I think.  When she came to the door, she asked how much it was.  I told her $29.70  She had four $10 bills and asked if I had change.  I didn't think I did, because it was only my second delivery of the night.  Each night I keep my tip money folded in half in my wallet to keep it seperate from money that is already in there so it's easier to count at the end of the night.  I didn't have change in my tip money, but I had 2 $5's in my wallet.  I gave those to her and she handed me 3 $10's and a $5 tip.  As I'm walking to the car I'm thinking, "Where is the ten that I changed for her"?  She kept it and handed me back a five for a tip.

I went back and her husband came to the door.  I explained that she only gave me enough to cover the pizza plus a tip, but that the $10 that I changed for her wasn't there.  He asked how much the total was and I told him she paid the total, but that she never gave me the ten dollars that I gave her two fives for.  He kept asking if she didn't give me enough to cover the total.  I was beginning to think I was going to have to explain it to him by saying, "If I had ten oranges..."  She came back to the door and acted like I was trying to rip them off or something.  I told her that when I gave her the fives, she should have given me the ten.  That has nothing to do with her total, that's my money.  I finally got them to understand and they gave me the other ten.

Luckily, the rest of the night went by without me having to explain basic math to anyone else.

Worked 4 hours, had 7 deliveries, and made $40 in tips.