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_75 (frequency VARCHAR, callsign VARCHAR, purpose VARCHAR, on_air_id VARCHAR)
### Question:
4tab of commercial broadcaster Radio Tab broadcasts at what frequency?
### Answer:
SELECT frequency FROM table_name_75 WHERE purpose = "commercial" AND on_air_id = "radio tab" AND callsign = "4tab"