<span>5х-2(х-3)=6х
</span>5х-2х+6=6х
5x-2x-6x = -6
- 3x = -6
x = -6:-3
x = 2
<span>6х-(2х-5)=2(3х-6)
</span>6x-2x+5 = 6x-12
6x-2x-6x = -12 -5
-2x = -17
x = -17:-2
x = 8.5
5с+15:6=80-8с:6 (сокращаем на :6) получаем
5с+15=80-8с
5с+8с=80-15
13с=65
с=65:13
с=5
12х-7=5х
12х-5х=7
7х=7
х=7:7
х=1