Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: 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?

### Accurate SQL ###

SELECT frequency FROM table_name_75 WHERE purpose = "commercial" AND on_air_id = "radio tab" AND callsign = "4tab"