CountDownTimer Help

I want to create a CountDownTimer, when my player touch a cube, the score increase of 10 (done) and the DownCountTimer should be start at 60 score and if this < 0 the player is destroy.

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

public class EatCube : MonoBehaviour
{
public string Tag;
public Text Letters;
public float Increase;

float Score = 60f;

void OnTriggerEnter(Collider other)
{
	if (other.gameObject.tag == Tag) {
		transform.localScale += new Vector3 (Increase, Increase, Increase);
		Destroy (other.gameObject);
		{
			Score += 10;
			Letters.text = "SCORE: " + Score;
		}
	}
}

}

It works !

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

public class Chrono : MonoBehaviour {

public Text Letters;
public float Destroy;

float Score = 60f;

void Update()
{
	Score -=Time.deltaTime;
	Letters.text = "SCORE: " + Score;
	if (Score < 0);

	{
		Destroy (gameObject);
	}

}

}

It doesn’t works

public Text Letters;
public float Destroy;
float Score = 60f;
void Update()
{
Score -=Time.deltaTime; <= here is your problem) change it to Score -= 1 * Time.deltaTime;
Letters.text = "SCORE: " + Score;
if (Score < 0);
{
Destroy (gameObject);
}