Please answer a question about the following article about Premier League:

There has been an increasing gulf between the Premier League and the Football League. Since its split with the Football League, many established clubs in the Premier League have managed to distance themselves from their counterparts in lower leagues. Owing in large part to the disparity in revenue from television rights between the leagues, many newly promoted teams have found it difficult to avoid relegation in their first season in the Premier League. In every season except 2001–02 and 2011–12, at least one Premier League newcomer has been relegated back to the Football League. In 1997–98 all three promoted clubs were relegated at the end of the season.

In the 1997-98 season how many new teams had to go back to the Football League?
In 1997–98 all three promoted clubs were relegated at the end of the season.