The county board shall meet at the office of the county clerk on the day fixed for the hearing, and shall first determine whether the requisite notice has been given. If it finds that due notice has not been given, it shall continue the hearing to a day to be fixed by the board, and order the notices to be served as provided in section 31-110. When the board finds that due notice has been given, it shall examine the report of the surveyor or engineer, including the apportionment made by him, and if it is in all respects fair and just, according to benefits, the board shall approve and confirm the same; but if it finds the apportionment to be unfair or unjust, it shall so order, and so amend the apportionment as to make it fair and just according to benefits.