2、 1:3 1:9

3、4:34:33:4

4. Positive and negative.

5、3:4

6、 1

7、0.9x = 0.6x 129 x = 7.5x 0.36/ 1x = 2/ 1x 4/ 1

x=7.3/0.9x=2.25/9x=8/ 1

x=8x=0.25x=4/3

8.10-{(10-4)/10}/{10-2)/10} *10 = 2.5km.

I hope you can adopt ~ ~ `` ~ ~ I am very lucky.