user: Question: what is the total number of goal different when the club is cf extremadura and the played is less than 38?
Columns: ['Position', 'Club', 'Played', 'Points', 'Wins', 'Draws', 'Losses', 'Goals for', 'Goals against', 'Goal Difference']
Types: ['real', 'text', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'Hércules CF', 38.0, 73.0, 21.0, 10.0, 7.0, 61.0, 30.0, 31.0]
SQL:

assistant: SELECT SUM("Goal Difference") FROM "Table" WHERE "Club" = 'cf extremadura' AND "Played" < 38.0;