You're trying to solve for x (get x by itself) so you divide 3x by 3, and what you do on one side you do to the other so you divide 29/3 which equals (x=9.66666667)
You want to have your x alone so you would get rid of the 3. to do that you must do the opposite of what it's saying which it is multiplying so you would divide 3 and do it on both sides. so 3/3 cancels eachother out and now you have to divide 29 and 3 and that is what x equals
If the line is horizontal, then all that have a 2 in the Y space will apply because the line goes across meaning that it won't change on the vertical axis.
