Two brothers took x cows to the market, and they sold each cow for x dollars. After selling the cows, they divided the money by giving $10 to the older brother, $10 to the younger brother, $10 to the older, $10 to the younger, and so on. At the last division of money, the older brother received $10, but the younger brother received less than $10. How many dollars must the younger brother have received at the last division?