2、 120÷9×4.5
= 120/2
=60dm?
3、[3 1.4×20+(3 1.4÷3. 14÷2)? ×3. 14]× 10
=[628+25×3. 14]× 10
=[628+78.5]× 10
=706.5× 10
=7065cm?
4、0. 15×[ 1.57×8×6]
=0. 15×6× 1.57×8
=0.9×8× 1.57
=7.2× 1.57
=11.304kg.
5、0.85×[(4/2)? ×3. 14×8]
=0.85×4×8×3. 14
=27.2×3. 14
=85.408 kg
6、 150÷(90÷ 15)
= 150÷6
=25 people
7. The length of the graph is 2800÷500=5.6 cm.
The drawing width is 1500 ÷ 500 = 3cm.
Buffer 200-500 = 0.4 cm
8、20× 15÷25
=20×3/5
=4×3
= 12 days
9. 1:30000000 is 1 cm on the map, but it is actually 300 kilometers.
So the actual distance from Chengdu to Beijing is 4.8×300= 1440 km.
Second,
1、x:6.5=4:3.25
3.25 times =6.5×4
x = 26÷ 3.25
x=8
2,7.5: x = 10/3: 1/3
7.5∶x= 10∶ 1
10x=7.5
x=0.75