difference between two vectors and an unknown

can't even work out where to start with this question, looked online at differences between vectors, found the difference between p & q to be 6root2. Any help very much appreciated.enter image description here

• Hint: what exactly does the condition $d(p,x)=d(q,x)$ mean? Literally, it says "the distance between p and x equals the distance between q and x." What does this tell you about the vector $x$? Surely you can think of such a vector. Nov 14 '17 at 21:46

Just take the mipoint of the two vectors $\left( \begin{array}{ccc} 3 \\ 1 \\ -3 \\ \end{array} \right).$