Random Damage delt (Game AS2) - Question

Im trying to add a random damage is delt when the Enemy attacks here is the code i have

onClipEvent (load)
{
    
    var scale = this._xscale;
}
onClipEvent (enterFrame)
{
    var distance = 150;
    var tx = this._x;
    var ty = this._y;
    var sx = _root.content.window.hero._x;
    var sy = _root.content.window.hero._y;
    if (Math.sqrt((sx - tx) * (sx - tx) + (sy - ty) * (sy - ty)) < distance)
    {
        if (tx < sx)
        {
            this.gotoAndStop(3);
            this._xscale = scale;
        } // end if
        if (tx > sx)
        {
            this.gotoAndStop(3);
            this._xscale = -scale;
        } // end if
    } // end if
    if (Math.sqrt((sx - tx) * (sx - tx) + (sy - ty) * (sy - ty)) > distance)
    {
        _root.content.window.enemy.gotoAndStop(1);
    } // end if
    if((_currentframe==3)and(this.hitTest(_root.content.window.hero))) {
_root.content.window.hp.health--




    } // end if
   
}

As you can see _root.content.window.hp.health-- is only dealing -1 per hit the enemy makes Lets say i want the damage to be random and between 5-10 how would i do this?
Thanks in advance!