Subject to the limitations set forth in section 8-303, each investing member shall be permitted to cast one vote for each hundred dollars of withdrawal value of his stock. Each borrowing member shall be permitted as a borrower to cast one vote, or to cast one vote for each one hundred dollars of the credit value of his stock. Fifteen or more members present at a regular or special meeting of members constitute a quorum. Voting may be by proxy if the instrument authorizing the proxy to vote shall have been executed by a member.