Sarah borrowed 12 books from the library. She returned 4 books and then borrowed 3 more. How many books does she have now?
12 - 4 + 3 = 11
Jake invites some friends to his birthday party. Lucy brought 2 balloons, Nancy brought 5 balloons and Jake had 10 balloons himself. How many balloons are there in total?
2 +5 + 10 = 20
Maria planted 15 flowers in her garden. Later, she planted 5 more flowers and gave away 4 to her neighbor. How many flowers does she have left?
15 + 5 - 4 = 16 flowers