[{"title": "Basic Addition", "content": "Add 69 + 72. Start in the ones place: 9 + 2 = 11. Since the sum is 10 or more, write 1 and carry 1. Continue to the tens place.", "solution": "69 + 72 = 141"}, {"title": "Word Problem", "content": "A library has 678 fiction books and 520 nonfiction books. How many books does the library have in total? Identify the operation: we are combining two quantities, so we add.", "solution": "678 + 520 = 1198 books"}]