Kayla is a speculator in the market for a rare French goat cheese known as Crottin de Chavignol. She entered into a futures contract with farmers from the small town of Chavignol, where the cheese is produced. The futures contract specifies that after 45 months, Kayla will purchase 3000 kilograms (kg) of Crottin de Chavignol at $220/kg. When the specified number of months has passed, the price of Crottin de Chavignol is $280/kg. What is Kayla\'s profit per kilogram? Please denote losses with a negative sign.