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_91 (week INTEGER, result VARCHAR)
### Question:
In what week was the Result L 15-13?
### Answer:
SELECT AVG(week) FROM table_name_91 WHERE result = "l 15-13"