Every city and town shall have the power to adopt a charter in the following manner: Whenever a petition for the adoption of a charter signed by fifteen percent of the qualified electors of a city, or in a town by fifteen percent, but not less than one hundred in number, of those persons qualified to vote on any proposition to impose a tax or for the expenditure of money shall be filed with the legislative body of any city or town the same shall be referred forthwith to the canvassing authority which shall within ten days after its receipt determine the sufficiency thereof and certify the results to the legislative body of said city or town. Within sixty days thereafter the legislative body of a city shall submit to its qualified electors and the legislative body of a town shall submit to the electors of said town qualified to vote upon a proposition to impose a tax or for the expenditure of money the following question: ”Shall a commission be appointed to frame a charter?” and the legislative body of any city or town shall provide by ordinance or resolution a method for the nomination and election of a charter commission to frame a charter consisting in a city of nine qualified electors and in a town of nine electors of said town qualified to vote upon a proposition to impose a tax or for the expenditure of money who shall be elected at large without party or political designation and who shall be listed alphabetically on the ballot used for said election. Such ordinance or resolution shall provide for the submission of the question and the election of the charter commission at the same time. Upon approval of the question submitted the nine candidates who individually receive the greater number of votes shall be declared elected and shall constitute the charter commission.