user: Question: How many episodes have been directed and written by Darrick Bachman and Brett Varon? 
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Storyboarded by', 'Original air date', 'Production code']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['21a', '1a', '"Panini for President"', 'Juli Hashiguchi', 'William Reiss', 'William Reiss', 'November6,2008', '202a']
SQL:

assistant: SELECT COUNT("Directed by") FROM "Table" WHERE "Written by" = 'Darrick Bachman and Brett Varon';