Question: What song had an index of M6?
SQL: SELECT "Song" FROM "2-15905451-5" WHERE "Index" = 'M6';

Question: For which song was the score 6.5 + 6.0 + 6.0 + 5.5 = 24.0?
SQL: SELECT "Song" FROM "2-15905451-5" WHERE "Score" = '6.5 + 6.0 + 6.0 + 5.5 = 24.0';