MVC - Fix Error - The type or namespace name 'RemoteAttribute' could not be found

The type or namespace name 'RemoteAttribute' could not be found (are you missing a using directive or an assembly reference?)

The type or namespace name 'Remote' could not be found (are you missing a using directive or an assembly reference?)

The type or namespace name 'ErrorMessage' could not be found (are you missing a using directive or an assembly reference?)