A final decision, determination or order adverse to a party in an adjudicatory proceeding shall be in writing or stated in the record and shall include findings of fact and conclusions of law or reasons for the decision, determination or order. Findings of fact, if set forth in statutory language, shall be accompanied by a concise and explicit statement of the underlying facts supporting the findings. A copy of the decision, determination or order shall be delivered or mailed forthwith to each party and to his attorney of record.