Any proposed ordinance may be submitted to the council by petition signed by electors of the city equal in number to the percentage hereinafter required.  The signatures, verification, authentication, inspection, certification, amendment and submission of such petition shall be the same as provided for petition under Section Thirty-six hereof.
   If the petition accompanying the proposed ordinance be signed by electors equal in number to twenty per centum of the votes cast for all candidates for mayor at the last preceding general election, and contains a request that the said ordinance by submitted to a vote of the people, if not passed by the council, such council shall either:
   (a)   Pass such ordinance without alteration within twenty days after attachment of the clerk’s certificate to the accompanying petition or,
   (b)   Forthwith, after the clerk shall attach to the petition accompanying such ordinance his certificate of sufficiency, the council shall call a special election, unless the general municipal election is fixed within ninety days thereafter, and at such special or general municipal election, of one is so fixed, such ordinance shall be submitted without alteration to the vote of the electors of said city.  But if the petition is signed by not less than ten per centum of the electors, as above defined, then the council shall within twenty days, pass said ordinance without change, or submit the same at the next general city election occurring not more than ninety nor less than thirty days after the clerk’s certificate of sufficiency is attached to said petition.
   The ballot used when voting upon said ordinance, shall contain these words: “for the ordinance,” and “against the ordinance,” (stating the nature of the proposed ordinance.)  If a majority of the qualified electors voting on the proposed ordinance shall vote in favor thereof, such ordinance shall thereupon become a valid and binding ordinance of the city; and any ordinance proposed by petition, or which shall be adopted by a vote of the people, cannot be repealed or amended except by a vote of the people.  Any number of proposed ordinances may be voted upon at the same election in accordance with the provisions of this section; but there shall not be more than one special election in any period of six months for such purpose.
   The council may submit a proposition for the repeal of any such ordinance or for amendments thereto, to be voted upon at any succeeding general city election; and should such proposition so submitted receive a majority of the votes cast thereon at such election, such ordinance shall thereby be repealed or amended accordingly.  Whenever any ordinance or proposition is required by this act to be submitted to the voters of the city at any election, the city clerk shall cause such ordinance or proposition to be published once in each of the newspapers published in said city; such publication to be not more than twenty nor less than five days before the submission of such proposition or ordinance to be voted on.