Question: How many percent more of the watchers for the repository of solution No.83855 than No.1502?
SQL: SELECT CAST(SUM(CASE WHEN T2.Id = 83855 THEN T1.Watchers ELSE 0 END) - SUM(CASE WHEN T2.Id = 1502 THEN T1.Watchers ELSE 0 END) AS REAL) * 100 / SUM(CASE WHEN T2.Id = 1502 THEN T1.Watchers ELSE 0 END) FROM Repo AS T1 INNER JOIN Solution AS T2 ON T1.Id = T2.RepoId