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