(a) A decision or order adverse to a party who has appeared and participated in a hearing must be in writing and include separately stated findings of fact and conclusions of law on the issues material to the decision or order. Findings of fact that are stated in statutory language must be accompanied by a concise and explicit statement of the underlying facts supporting the findings.
(b) A decision or order entered after a hearing becomes final and appealable 15 days after the date it is entered unless a party files a motion for rehearing before that date. If the motion for rehearing is overruled, the decision or order becomes final and appealable on the date the order overruling the motion is entered.

(c) Each party to a hearing shall be promptly notified personally or by mail of a decision, order, or other action taken in respect to the subject matter of the hearing.