Among the repository "3", how many methods whose comments is XML format?
repository refers to RepoId; RepoId = 3; method refers to Name; method whose comment is XML format refers to CommentIsXml = 1;
SELECT COUNT(T2.SolutionId) FROM Solution AS T1 INNER JOIN Method AS T2 ON T1.Id = T2.SolutionId WHERE T1.RepoId = 3 AND T2.CommentIsXml = 1