Answer:
The minimum number and type of fire extinguishers required for a 10,000 sq. ft. place for public assembly with a 20'x 90' commercial kitchen would depend on the specific fire code requirements of the jurisdiction where the building is located.
In general, commercial kitchens require Class K fire extinguishers, which are specifically designed for use on fires involving cooking oils and fats. The size and number of extinguishers required would depend on the size of the kitchen, the type of cooking equipment present, and other factors.
It is recommended to consult with local fire authorities or a fire protection specialist to determine the specific fire code requirements for the building in question.