Which problem represents the separate, start unknown structure?
◦ Maryann had 3 library books before she checked out 2 more. How many did she have all together?
◦ Maryann had 5 library books before she returned 2 of them. How many does she have now?
◦ Maryann had some nonfiction books and 2 fiction. She now has 8 books. How many did she begin with?
◦ Maryann had 9 library books and Jim had 4. How many more did Maryann have than Jim?