2. (800× 60) ÷ 8 ÷ 30×15×12 = 36,000 (square meters)

3. (65+67.5) × 8+52 =1152 (m)

4650-(50+52) × 4 = 242km

5, 1 ÷ ( 1/5+ 1/ 10) = 1 ÷ 1 × 15/4 =

6、 1/3 ÷ 4 +2/5÷ 10 = 1/ 12 + 1/25 = 9%