SCHEMA:
CREATE TABLE table_name_87 (net_yards INTEGER, yards_per_attempt VARCHAR, touchdowns VARCHAR, attempts VARCHAR)
USER:
What are the average net yards that have 9 as the touchdowns, 145 as the attempts, and yards per attempt greater than 4.8?

QUERY:
SELECT AVG(net_yards) FROM table_name_87 WHERE touchdowns = 9 AND attempts = 145 AND yards_per_attempt > 4.8