Who was the opponent with the record of 15-21-6?
CREATE TABLE table_name_23 (opponent VARCHAR, record VARCHAR)
SELECT opponent FROM table_name_23 WHERE record = "15-21-6"
### Context: CREATE TABLE table_name_23 (opponent VARCHAR, record VARCHAR) ### Question: Who was the opponent with the record of 15-21-6? ### Answer: SELECT opponent FROM table_name_23 WHERE record = "15-21-6"