Arrays - picking a random object

I've been trying to find a concrete answer for this question, but all answers have not been working

The player has to drag & drop several hints on spaces and all of the spaces should accept the hint. I was trying to work with arrays, but the transform.position does not work in this context. so far the script looks like this:

     private GameObject [] tri;
     private GameObject []space;
     private Vector3 screenPoint;
     private Vector3 offset;
 
     void OnMouseDown() {
 
         offset = gameObject.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z));
     }
 
     void OnMouseDrag()
     {
         tri = GameObject.FindGameObjectsWithTag("hints");
         Vector3 curScreenPoint = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z);
         Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint) + offset;
         tri[].transform.position = curPosition;
     }
     void Update () {
         space = GameObject.FindGameObjectsWithTag("space");
         Vector3 V = tri[].transform.position;
         Vector3 V2 = space[1].transform.position;
         if (Mathf.Abs(V.x - V2.x) < 1f )
         {
             Debug.Log("I'm there");
             LockPlace();
 
         }
     }
     void LockPlace(){
         tri[].transform.position = space[1].transform.position;
 
     }
 }