What is the average goal difference using slavia sofia club?
CREATE TABLE table_name_8 (goal_difference INTEGER, club VARCHAR)
SELECT AVG(goal_difference) FROM table_name_8 WHERE club = "slavia sofia"
### Context: CREATE TABLE table_name_8 (goal_difference INTEGER, club VARCHAR) ### Question: What is the average goal difference using slavia sofia club? ### Answer: SELECT AVG(goal_difference) FROM table_name_8 WHERE club = "slavia sofia"