标准答案:
(3 + 3 ÷ 7) × 7=24
(3 + (3 ÷ 7)) × 7=24
(3 ÷ 7 + 3) × 7=24
((3 ÷ 7) + 3) × 7=24
7 × (3 + 3 ÷ 7)=24
7 × (3 + (3 ÷ 7))=24
7 × (3 ÷ 7 + 3)=24
7 × ((3 ÷ 7) + 3)=24