CREATE TABLE table_name_67 (fixtures INT, round VARCHAR, clubs_involved VARCHAR)

In the sixth round, what is the sum of fixtures when there were more than 15 clubs involved?
SELECT SUM(fixtures) FROM table_name_67 WHERE round = "sixth round" AND clubs_involved > 15
SELECT SUM("fixtures") FROM "table_name_67" WHERE "clubs_involved" > 15 AND "round" = "sixth round"