Edit in JSFiddle

angular.module('myapp', []).controller('HomeController', ['$scope', function($scope) {
    $scope.fields = {
        name: '',
        age: ''
    };
}]);

<div ng-app="myapp">
    <div ng-controller="HomeController">
        <div>Name: <input type="text" ng-model="fields.name" name="name" /></div>
        <div ng-if="name != 'Tom'">Age: <input type="text" ng-model="fields.age" name="age" /></div>
        <div>Hello, {{fields.name}} {{fields.age}}!</div>
    </div>
</div>