Every decision and order adverse to a party to the proceeding, rendered by an agency in a contested case, shall be in writing or stated in the record and shall be accompanied by separate findings of fact and conclusions of law. If any party to the proceeding has filed proposed findings of fact, the agency shall incorporate in its decision a ruling upon each proposed finding so presented. The agency shall notify the parties to the proceeding by delivering or mailing a certified copy of the decision and order and accompanying findings and conclusions within a reasonable time to each party or to the party’s attorney of record.