Simple calculation for difference between two times

Hey, I need help with a really simple calculation between two different times.

Simple final time - intial time = difference between times.

I’m just starting out and having some real teething issues in working things out, all I get out is 0hours 0mins.

This is what I have:

function addTime (event:MouseEvent):void
var time1:Number;
var time2:Number;
var answer:int;


inputThree.text = answer + 'Hours' + answer + 'Minutes';


myButton.addEventListener (MouseEvent.CLICK,addTime)

Thank you to anyone for any help, I just want to be able to get this working and wrap my head around it.