this is crazy. I like to correct myself and say he lost $10 or $13.
Buyer scam him of $3, he lost a widget (meaning his inventory has decreased by $3), and he gave buyer $7.
Remember all this started out with a fake $10 so every transaction from the seller is a deduction from his overall total.
$10 or $13 is my final answer. I think I used up all of my lifeline
