Section 34. (a) No amendment to the project instrument may be adopted except pursuant to this section or section thirty-three. The project instrument may specify other matters to be determined by referendum of the owners and may permit the managing entity to select matters to be determined in said manner.
(b) If an amendment to a project instrument proposed by the managing entity, or other matter, is to be determined by referendum, the managing entity shall prepare and, not less than thirty or more than one hundred and eighty days before the votes are be counted, shall mail to each owner a ballot stating each matter to be determined and affording the opportunity to vote ''yes'' or ''no'' on each matter. The ballot may be accompanied by a letter from the managing entity recommending a particular decision.
(c) On the date specified pursuant to clause (2) of subsection (c) of section thirty-two, the managing entity shall examine the ballots that have been returned and calculate the vote accordingly. A simple majority of the votes counted shall determine each matter unless the project instrument specifies a larger majority, but no matter may be determined by referendum unless the ballots favoring the majority decision represent at least twenty-five per cent of the votes allocated to all owners.