Well I don't know what you mean by justify, but here is how I would go about it:
2(3x-4)=5x+6
Distribute the 2:
6x-8=5x+6
Add the 8 to the other side, because it's a negative
6x-8=5x+6
+8 +8
Then you would have 6x=5x+14
Subtract the 5x
6x=5x+14
-5x
1x=14
Divide by 1
x=14
Your answer is x=14