i dont get this code, please help

Type `Bullet’ does not contain a definition for #speed’ and no extension method #speed’ of type #Bullet’ could be found #are you missing a using directive or an assembly reference?
what is the problem???
```csharp
**using UnityEngine;
using System.Collections;

public class Gun : MonoBehaviour {
public GameObject bullet;
public float speed;

// Use this for initialization
void Start () {
    bullet.GetComponent<Bullet>().speed = speed;

}

// Update is called once per frame
void Update () {

}

public void Shoot()
{
    Instantiate(bullet, transform.position, transform.rotation);
}

}**
```

your bullet script doesn’t have a public variable called “speed”…

This.