Sarah had a collection of stamps. She decided to give some away over three weeks. In the first week, she gave away of her stamps plus 5 stamps. In the second week, she gave away of the remaining stamps plus 8 stamps. In the third week, she gave away of the remaining stamps plus 10 stamps. After the third week, she had 50 stamps left. How many stamps did Sarah have initially?
120
138
150
160