Table schema:
CREATE TABLE table_name_25 (date_of_vacancy VARCHAR, position_in_table VARCHAR, outgoing_manager VARCHAR)

Question: what is the date of vacancy when the position in table is 16th and the outgoing manager is russell slade?
SQL: SELECT date_of_vacancy FROM table_name_25 WHERE position_in_table = "16th" AND outgoing_manager = "russell slade"