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_28 (audio VARCHAR, just_ratio VARCHAR)
### Question:
what is the value of the audio with a just ratio 21:20
### Answer:
SELECT audio FROM table_name_28 WHERE just_ratio = "21:20"