正文

1. 2 × 5 + 3 ÷ 2 = 2. 8 - 4 × 3 + 2 = 3. 7 ÷ (2 + 1) = 4. 5 × 4 - 3 ÷ 2 = 5. 9 + 6 × 2 - 4 =