If a majority of the voters of the metropolitan area approve the issuance of bonds as provided in Sections 20-30 and 20-35, the Authority shall have power to levy and collect annually a sum sufficient to pay for the annual principal and interest charges on such bonds.
     Such taxes proposed by the Authority to be levied upon the taxable property within the metropolitan area shall be levied by ordinance. After the ordinance has been adopted it shall, within 10 days after its passage, be published once in a newspaper published and having a general circulation within the metropolitan area. A certified copy of such levy ordinance shall be filed with the county clerk no later than the 3rd Tuesday in September in each year. Thereupon the county clerk shall extend such tax.