How to change a variable of a script from other script in unity C# ?

here is my code

using UnityEngine;
using System.Collections;

public class _destroyBust : MonoBehaviour {


	private GameObject temp;
	private string name;
	public GameObject bustPrefab;
	
	
	void OnTriggerEnter(Collider other) {
		
		
		name=other.gameObject.tag; 
		Debug.Log(name);
		temp= GameObject.FindGameObjectWithTag(name);
		//Destroy(temp,3);
		Instantiate(bustPrefab,new Vector3(temp.transform.position.x,temp.transform.position.y,temp.transform.position.z),temp.transform.rotation) ;
		Destroy(temp);
	}
}






using UnityEngine;
using System.Collections;

public class _optionMovement : MonoBehaviour {

public GameObject _bubbleThree;
public static float speedY;
public  static float speedX;
	
	void Start () {


		speedY=100f;
		speedX=150f;
		_bubbleOne.rigidbody.velocity = new Vector3(0,2.5f, 0);
		_bubbleThree.rigidbody.velocity = new Vector3(0,2.5f, 0);


	}

void update()
{
int[] dir=new int[]{-2,2,-2,2};

			int ran=Random.Range(0,dir.Length);
_bubbleThree.rigidbody.AddForce(speedX*Time.deltaTime*dir[ran],-(speedY+50f)*Time.deltaTime*dir[ran], 0);}
}
}

I just want to change the value of speedY and speedX of _optionMovement.cs script from _destroyBust.cs script when trigger happened but I don’t know how to do it.please help me out

_optionMovement.speedY = 999f;

And update() should be Update()…

Please try following some tutorials:

https://unity3d.com/learn/tutorials/modules/intermediate/scripting/statics