Mary has a mystery book library. She started with 72 mystery books at the beginning of the year. She joined a book club that sent her 1 book each month of the year. She went to a bookstore halfway through the year and bought 5 more books, then bought 2 books at yard sales later. Her daughter gave her another book for her birthday, and her mother gave her a series of 4 books when Mary visited her. She donated 12 books she didn't want to read again to a charity shop and sold 3 to a used book store. How many books did she have at the end of the year?
Mary got 1 * 12 = <<1*12=12>>12 books from the book club.
She bought 5 + 2 = <<5+2=7>>7 books.
She was given 1 + 4 = <<1+4=5>>5 books.
She got rid of 12 + 3 = <<12+3=15>>15 books.
Thus, at the end of the year she had 72 + 12 + 7 + 5 - 15 = <<72+12+7+5-15=81>>81 books.
#### 81