Concatenate multiple rows to single having similar group

SELECT
    Id,Name,
    Stuff(
    (SELECT '/' + State
       FROM Table_3 t2
        WHERE t2.Id=t1.Id and t2.Name=t1.Name
        FOR XML PATH(''),type).value('.','nvarchar(max)'), 1, 1, '') AS Class
FROM
    Table_3 t1
GROUP BY Id,Name