This may be tricky considering that you have only values of X, which are not equated to anything. In addition, considering that, you have only one unknown and nothing to compare it with, it might be a little bit tricky for you. However, if you add them you will get 12X and if you equate it to 0, then you will get X=0.
Based on Order of Operations, you would combine like-terms on the left side of the =. Assuming that the right side is then 0, you should have 12x=0, and because your variable, x, is not alone, you divide 0 by 12, giving you x=0.