CREATE TABLE table_name_75 (frequency VARCHAR2, callsign VARCHAR2, purpose VARCHAR2, on_air_id VARCHAR2)

4tab of commercial broadcaster Radio Tab broadcasts at what frequency?
SELECT frequency FROM table_name_75 WHERE purpose = "commercial" AND on_air_id = "radio tab" AND callsign = "4tab"
SELECT "frequency" FROM "table_name_75" WHERE "4tab" = "callsign" AND "commercial" = "purpose" AND "on_air_id" = "radio tab"