3(2x - 4) - 6 - 3x = 12
6x - 12 - 6 - 3x = 12
We could now combine like terms so that the equation could get more simple.
6x and 3x are like terms, since they both have 'x'.
6x - 3x = 3x
6x - 12 - 6 - 3x = 12
-12 - 6 - 3x = 12
-18 - 3x = 12
+18 +18
-3x = 30
x = -10
We have our answer, x = -10