Notice of an election must be given by publication in a newspaper and by posting at one (1) or more specified locations. The City Secretary shall post properly executed copies of the election notice in three (3) public places within the city. The last day for posting notice shall be the twenty-first day before the election. The period for publishing notice in the official newspaper is no earlier than the thirtieth (30th) day or later than the tenth (10th) day before the election day.