how to update ng-repeat value with an input inside it?

I have the following code

<tr ng:repeat="item in invoice.items"  >
                    <td><a>{{item.nombre}}</a></td>
                    <td><a>{{item.existencia}}</a></td>
                    <td>{{item.embalaje}}</td>
                    <td><input ng:model="item.cantidad" ng:value="0" required size="4" ng:required ng:validate="integer"></td> 
                    <td><a>{{item.valorunidad}}</a></td>
                    <td><a>19%</a></td>
                    <td>{{item.valorunidad * 0.19| currency}}</td>       
                    <td>{{ (item.valorunidad) * item.cantidad | currency}}</td>

                    <td><a href ng:click="removeItem(item)"  class="btn btn-primary btn-block" >X</a></td>
                </tr>

How can I do that, as I type in the quantity in ng: model="item.quantity" the values of the list are updated and I modified the last operation: {{(item.valorunity) * item.quantity | currency}}