Question 530055
In order to remove the 6 from the left side it is necessary to do the opposite of what is there. In this case it is a +6 so you need to subtract to remove it.
In equations it is always necessay to do the same thing to both sides, thus 18-6=12.
Another thought, if you had 3x-6=18 you would add 6 to both sides to remove it from the left side. Always do the opposite to what is there.
Does that help?
Bob