CREATE TABLE table_name_42 (city_of_license VARCHAR, frequency_mhz VARCHAR)

Which City of license has a Frequency MHz of 91.5 fm?
SELECT city_of_license FROM table_name_42 WHERE frequency_mhz = "91.5 fm"
SELECT "city_of_license" FROM "table_name_42" WHERE "91.5 fm" = "frequency_mhz"