1) 2х=18-х
2х+х=18
3х=18
х=6
2) 7х+3=30-2х
7х+2х=30-30
9х=27
х=3
3) 7-2х=3х-18
-2х-3х=-18-7
-5х=-25
х=5
4) 0.2х+2.7=1.4-1.1х
0.2х+1.1х=1.4-2.7
1.3х=-1.3
х=-1
5) 5.4-1.5х=0.3х-3.6
-1.5х-0.3х=-3.6-5.4
-1.8х=-9
