What is Class, when Power is 78 Watts?
CREATE TABLE "s_rebroadcaster_of_cbqt_fm" (
  "city_of_license" text,
  "identifier" text,
  "frequency" text,
  "power" text,
  "class" text,
  "rec_net" text
);
SELECT "class" FROM "s_rebroadcaster_of_cbqt_fm" WHERE "power"='78 watts';