CREATE TABLE table_name_58 (erp_w NUMBER, frequency_mhz VARCHAR2)

Which ERP W is the lowest one that has a Frequency MHz of 91.3?
SELECT MIN(erp_w) FROM table_name_58 WHERE frequency_mhz = 91.3
SELECT MIN("erp_w") FROM "table_name_58" WHERE "frequency_mhz" = 91.3