8x-12,8=0 ; 12-x=2-5; 9x-(6x+10)=20; 4(x-1)=3x+(x-4)

8x-12,8=0;
8x=12,8;
x=1,6

12-x=2-5;
-x=-15;
x=15

9x-(6x+10)=20;
9x-6x-10=20;
3x=30;
x=10

4(x-1)=3x+(x-4);
4x-4=3x+x-4;
-4=-4
x=0