Unless otherwise provided in the articles of incorporation, a majority of votes of the shares, entitled to vote on a matter, represented in person or by proxy, shall constitute a quorum for consideration of such matter at a meeting of shareholders, but in no event shall a quorum consist of less than one-third of the votes of the shares entitled so to vote. If a quorum is present, the affirmative vote of the majority of the votes of the shares represented at the meeting and entitled to vote on a matter shall be the act of the shareholders, unless a greater number of votes or voting by classes is required by this Act or the articles of incorporation. The articles of incorporation may require any number or percent greater than a majority of votes up to and including a requirement of unanimity to constitute a quorum.