user: Question: What is the average overall that has a pick less than 20, north carolina as the college, with a round less than 8?
Columns: ['Round', 'Pick', 'Overall', 'Name', 'Position', 'College']
Types: ['real', 'real', 'real', 'text', 'text', 'text']
Sample row: [6.0, 21.0, 159.0, 'Tony Green', 'RB', 'Florida']
SQL:

assistant: SELECT AVG("Overall") FROM "Table" WHERE "Pick" < 20.0 AND "College" = 'north carolina' AND "Round" < 8.0;