1)4х-20=0

4х=20

х=20/4

х=5

2)3х-5=4х+1

3х-4х=1+5

-х=6

х=-6

3)2(х+7)=9-2х

2х+14=9-2х

2х+2х=9-14

4х=-5

х=-5/4

х=-1,25