Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_21831 ( "Year" real, "Network" text, "Play-by-play" text, "Colour commentator(s)" text, "Sideline reporters" text, "Pregame host" text, "Pregame analysts" text )

### Question ###
Who did the play-by-play when the pregame host was Brian Williams and the sideline reporters were Steve Armitage and Brenda Irving?

### Accurate SQL ###

SELECT "Play-by-play" FROM table_21831 WHERE "Pregame host" = 'Brian Williams' AND "Sideline reporters" = 'Steve Armitage and Brenda Irving'