Score not wokring the way I want it to

Im making a small game about the Area 51 raid and I want the score increase when I go right and decrease when I go left (going to negative if at 0). With the code I have now, it increases as long as I am moving away from the starting point. I know its increasing because I’m using the Vector2.Distance method, but there isn’t a displacement method, so I can’t figure out what to do. Here is my code and please feel free to make heavy changes to the code if it makes the score work how I want it to. Thanks.

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

public class GameSession : MonoBehaviour {

 [SerializeField] float score = 0;

 [SerializeField] Text scoreText;

 public Transform player;

 // Start is called before the first frame update
 void Start()
 {
     scoreText.text = score.ToString();
     transform.position = player.position;
 }

 // Update is called once per frame
 void Update()
 {
     if (player != null)
     {
         score = 10 * Mathf.RoundToInt(Vector2.Distance(player.position, transform.position));
         scoreText.text = score.ToString();
     }
 }

}