[{"title": "Basic Subtraction", "content": "Subtract 77 − 58. Ones place: 7 − 8. Since 7 < 8, borrow from the tens place.", "solution": "77 − 58 = 19"}, {"title": "Checking with Addition", "content": "If 85 − 37 = 48, check by adding: 48 + 37 = 85. ✓ Correct.", "solution": "85 − 37 = 48"}]