7×[3÷7-(-3)]＝24
1: 7 × (3 ÷ 7 + 3)
2: 7 × ((3 ÷ 7) + 3)
3: 7 × (3 + 3 ÷ 7)
4: 7 × (3 + (3 ÷ 7))
5: (3 ÷ 7 + 3) × 7
6: ((3 ÷ 7) + 3) × 7
7: (3 + 3 ÷ 7) × 7
8: (3 + (3 ÷ 7)) × 7