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