The city council of a city of the metropolitan class is authorized to call, by ordinance, special elections and to submit at such elections such questions and propositions as may be authorized by law to be submitted to the electors at a special election. Unless otherwise specifically directed, it shall be sufficient to give, in the manner required by law, thirty days' notice of the time and place of holding such special election. Unless otherwise specifically designated, a majority vote of the electors voting on any proposition shall be regarded sufficient to approve or carry such proposition. The vote at such special election shall be canvassed by the authority or officer authorized to canvass the vote at the general city election and the result of such election certified or declared and certificate of election, if required, shall be issued.