CREATE TABLE table_name_27 (home_team VARCHAR(255), date VARCHAR(255), tie_no VARCHAR(255), away_team VARCHAR(255))
With Sheffield United as the away team and the date, what home team has a tie no of 15?
    
SQL: SELECT home_team FROM table_name_27 WHERE tie_no = "15" AND away_team = "sheffield united" AND date = "sheffield united"