By moving -4 to the right hand side, we get
Now, by the properties of the absolute values, this last equation becomes in 2 conditions:
From condition a), by moving 12 to the right hand side, we get
and x is given by
Now, from condition b), by moving 12 to the right hand side, we have
then, x is given by
Therefore, the answer is the union of both solution, that is, the answer is the third option: x=-1, 9