Table: fa_cup_matches_21
Columns: tie_no
home_team
score
away_team
attendance

Question: How many ties occurred with a score of 2–2?
SQL: SELECT "tie_no" FROM fa_cup_matches_21 WHERE "score" = '2–2'

Question: Who is the home team when Preston North End is the away team?
SQL: SELECT "home_team" FROM fa_cup_matches_21 WHERE "away_team" = 'preston north end'