calculate an average with 2 variables - actionscript-3

Question

I'm creating a game in AS3.
I've got a toolbar with a string for money, one for happiness and one for tourists.
The happiness is coded like that :
var happyString:String = "0";
var happyNumber = Number(happyString);
bonheur.text = String(happyString);
trace(happyString);
I'd like the "happy" value depends on two variables (invisibles for the player).
A variable "confort" and a variable "distraction".
And the "happy" value would be = ("confort"+"distraction")/2
I don't really know how to do it though...
I did that :
var confortString:String = "0";
var confortNumber = Number(confortString);
var distractionString:String = "0";
var distractionNumber = Number(distractionString);
stageRef.addEventListener("PiscineBuilt", piscineVariables, false, 0, true);
private function piscineVariables(event):void{
confortNumber = Number(confortString) +3;
trace(confortNumber);
distractionNumber = Number(distractionString) +20;
trace(distractionNumber);
}
First, I don't think the "confort" and "distraction" values are added each time the function is called...
Second, How I can do in order to have the value "happy" (which is visible for the player in the toolbar) equal to ("confort"+"distraction")/2
var happyString:String = distractionNumber + confortNumber ;
var happyNumber = Number(happyString);
bonheur.text = String(happyString);
trace(happyString);
??
Thank you for your help !
EDIT
So, here I am now :
var confort:Number = 0;
var distraction:Number = 0;
var happy:Number = 0;
happy=(confort+distraction)/2;
bonheur.text=String(happy);
stageRef.addEventListener("PiscineBuilt", piscineVariables, false, 0, true);
private function piscineVariables(event):void{
confort+=10;
distraction+=30;
trace(confort);
trace(distraction);
}
GOOD:
Forgot to change the value of my bonheur.text :
bonheur.text = String( Number(bonheur.text ) +(confort+distraction)/2 );

Answer 1

Why do you store strings and make numbers dependant on them? You just do:
var confort:Number = 0;
var distraction:Number = 0;
var happy:Number = 0;
And whenever your numbers are updated, you should also update the text in bonheur:
happy=(confort+distraction)/2; // making an average is as simple as this, if you're not using strings!!!
bonheur.text=String(happy);