Fade to a percentage

programming flash
1

Hi all. I’m using the code below to fade in a movieclip and I’d like to know how I halt the fade in at 80% say. Can anyone help me out?

onClipEvent (enterFrame) {
this._alpha = _alpha +6;
}

Ta.

2 
onClipEvent (enterFrame) {
	if (this._alpha < 80) {
		this._alpha = _alpha + 6;
	}
}
3

Thank you so very much. Works like a charm.