Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_4 (goal_difference INTEGER, goals_against VARCHAR, losses VARCHAR)
### Question:
What is the average goal difference with 51 goals scored against and less than 17 losses?
### Answer:
SELECT AVG(goal_difference) FROM table_name_4 WHERE goals_against = 51 AND losses < 17