1. 计算：5/6 + 3/4
答案：5/6 + 3/4 = (5*4 + 3*6) / (6*4) = 47/24
2. 计算：2/3 - 1/4
答案：2/3 - 1/4 = (2*4 - 1*3) / (3*4) = 5/12
3. 计算：3/5 × 2/3
答案：3/5 × 2/3 = (3*2) / (5*3) = 6/15 = 2/5
4. 计算：4/7 ÷ 2/5
答案：4/7 ÷ 2/5 = (4/7) × (5/2) = 20/14 = 10/7
5. 计算：7/8 + 1/2 - 3/4
答案：7/8 + 1/2 - 3/4 = (7*2 + 1*4 - 3*2) / (8*2) = 9/16
1.
45+15×6= 135
2.
250÷5×8=400
3.
6×5÷2×4=60
4.
30×3+8=98
5.
400÷4+20×5= 200
6.
10+12÷3+20=34
7.
(80÷20+80)÷4=21
8.
70+(100-10×5)=120
9.
360÷40= 9
