12. Subject to contract between the partners-(a) every partner has a right to take part in the conduct of the business; (b) every partner is bound to attend diligently to his duties in the conduct of the business; (c) any difference arising as to ordinary matters connected with the business may be decided by a majority of the partners, and every partner shall have the right to express his opinion before the matter is decided, but no change may be made in the nature of the business without the consent of all the partners; and (d) every partner has a right to have access to and to inspect and copy any of the books of the firm.