calling_action_score.cs

score_manager myScoreManager;

void Start() {

      myScoreManager = GetComponent<score_manager>();

  }
  
void OnCollisionEnter(Collision target) {

      if (target.gameObject.name == "dragon") {
          onHit();
          myScoreManager.addScore(50);
      }

      if (target.gameObject.tag == "potion" ) {
          Destroy(target.gameObject);
          myScoreManager.addScore(20);

      }
  }