Shelby was having a movie party for her birthday. She and her mom made a dozen bags of buttered popcorn and 10 bags of caramel popcorn. Her brother Alan took 3 bags of buttered popcorn and 1 bag of caramel popcorn for his friends. How many bags of popcorn does Shelby have left for the party?
Please reason step by step, and put your final answer within \boxed{}.
user