what is the class of the station with erp w more than 30?
CREATE TABLE "low_power_translators" (
  "call_sign" text,
  "frequency_m_hz" real,
  "city_of_license" text,
  "erp_w" real,
  "class" text,
  "fcc_info" text
);
SELECT "class" FROM "low_power_translators" WHERE "erp_w">30;