By a resolution entered on its minutes, the board of supervisors of each affected county shall declare the district formed if:
(a) A majority of the votes cast at the election is for the formation of the district.
(b) A majority of the votes cast in a majority in number of the cities included in whole or in part in the district, counting all of the unincorporated territory in each affected county as a city for this purpose, is for the formation of the district.