CREATE TABLE table_name_4 (goal_difference NUMBER, goals_against VARCHAR2, losses VARCHAR2)

What is the average goal difference with 51 goals scored against and less than 17 losses?
SELECT AVG(goal_difference) FROM table_name_4 WHERE goals_against = 51 AND losses < 17
SELECT AVG("goal_difference") FROM "table_name_4" WHERE "goals_against" = 51 AND "losses" < 17