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_27714573_1 (directed_by VARCHAR, us_viewers__millions_ VARCHAR)
### Question:
who are the directors of the episode that had 20.5 millions of north american viewers? 
### Answer:
SELECT directed_by FROM table_27714573_1 WHERE us_viewers__millions_ = "20.5"