10х+7=8х-9
10х-8х=-9-7
2х=-16
х=-16÷2
х=-8
20-3х=2х-45
-3х-2х=-45-20
-5х=-65
х=-65÷(-5)
х=13
2,7+1,9х=2х-1,5
1,9х-2х=-1,5-2,7
-0,1х=-4,2
х=-4,2÷(-0,1)
х=42
-3(х-4)=5х-12
-3х+12=5х-12
-3х-5х=-12-12
-8х=-24
х=-24÷(-8)
х=3
(16х-5)-(3-5х)=6
16х-5-3+5х=6
16х+5х=6+5+3
21х=14
х=14÷21
х=2/3