по первому:

1. 2х-х=7-10

х=-3

2. 2+3х-9=2х-6

3х-2х=9-2-6

х=1

3. 4х+2/3= 2х-4/3

х=-1

4. -2/5*х+6=1/2*х-1/2

-9/10*х=-13/2

х=65/9

5. 4х-3х+21=2х+15

-х=15-21

х=6

5. 2х+2+1/2*х-1/2=1/2-2

3/4*х=3/2

х=2