4*x+7+5*x=6*x+12+2*x
4x+7+5x=6x+12+2x
4x+5x-6x-2x= 12-7
x= 5
1-2*x-12-7*x=3*x+10-5*x
1-2x-12-7x=3x+10-5x
-2x-7x+5x-3x= 10-1+12
-7x= 21 / :(-7)
x= -3
