Table schema:
CREATE TABLE table_name_73 (goals_against INTEGER, goals_for VARCHAR, points VARCHAR, wins VARCHAR)

Question: How many goals against were scored when the points were smaller than 13, the wins were smaller than 3, and the goals for were smaller than 15?
SQL: SELECT SUM(goals_against) FROM table_name_73 WHERE points < 13 AND wins < 3 AND goals_for < 15