[{"id": 1, "type": "short_answer", "skill": "subtraction", "question": "Calculate: 80 − 35", "difficulty": "medium", "explanation": "Subtract by place value, borrowing as needed.", "needs_review": false, "correct_answer": "45"}, {"id": 2, "type": "multiple_choice", "skill": "subtraction", "options": ["45", "43", "115", "46"], "question": "What is 80 − 35?", "difficulty": "easy", "explanation": "80-35=45", "needs_review": false, "correct_answer": "45"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 17", "difficulty": "medium", "explanation": "Multiply: 9×17=153", "needs_review": false, "correct_answer": "153"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 12 × 5", "difficulty": "medium", "explanation": "Multiply: 12×5=60", "needs_review": false, "correct_answer": "60"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 17", "difficulty": "medium", "explanation": "Multiply: 9×17=153", "needs_review": false, "correct_answer": "153"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 10 × 14", "difficulty": "medium", "explanation": "Multiply: 10×14=140", "needs_review": false, "correct_answer": "140"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 13 × 6", "difficulty": "medium", "explanation": "Multiply: 13×6=78", "needs_review": false, "correct_answer": "78"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 19 × 7", "difficulty": "medium", "explanation": "Multiply: 19×7=133", "needs_review": false, "correct_answer": "133"}]