How to get the result of adding two number in third text box

Question

It is not at al giving the result. Help me to find where I was wrong

 

View:

@{

ViewBag.Title = "Home Page";

}

<script src="scripts/angular.min.js"></script>

<script src="~/Scripts/AngularJsDemo.js"></script>

<div ng-app="MyFinancialsApp">

<div ng-controller="MyController">

<div >

GrossWanges: <input ng-model="a" type="text" ng-change="UpdateVal()"/>

</div>

<div>

OverTime : <input ng-model="b" type="text" ng-change="UpdateVal()" />

</div>

<div>

ChildSupport : <input ng-model="c" type="text" ng-change="UpdateVal()" />

</div>

<div style="float:right">

<p>Total : {{a--b--c}}</p>

</div>

</div>

</div>

 

 

AngularJs:

var FinancialsApp = angular.module("MyFinancialsApp", [])

.controller("MyController",function($scope)){

$scope.UpdateVal=function(){

$scope.TotalVaue=($scope.a)+($scope.b)+($scope.c);

}

});