how to add two scores to get total

Heading ##i am trying to add the scores from different scene and add them to get total score after the round 3. will i make another gameobjet and script for this or just make a line of code inside the gamecontroller? Please help.

public void Endround()
        isRoundActivex = false;

//score from round 3
        HighscoreDisplaytextx.text = "Round 3 Score: " + roundtwoDataController.GetHighestScorex().ToString();

        //score from round 1
        roundOneScore = PlayerPrefs.GetInt("Player_Score");
        GameOneScore.text = "ROUND 1 SCORE: " + roundOneScore.ToString();

        questionDisplayx.SetActive (false);

  public void totalscore()

//adding score round1 and round3
        playerScorex += roundOneScore;
        TotalScore.text = "TOTAL SCORE: " + totalScore.ToString();

It looks like you added the two scores with the line “playerScorex += roundOneScore;”, but the TotalScore.text line should read:
TotalScore.text = "TOTAL SCORE: " + playerScorex.ToString();