CREATE TABLE table_2190919_3 (avg_finish VARCHAR2, team_s_ VARCHAR2)

With team #21/#07 ss-green light racing, what was the average finish number?
SELECT avg_finish FROM table_2190919_3 WHERE team_s_ = "#21/#07 SS-Green Light Racing"
SELECT "avg_finish" FROM "table_2190919_3" WHERE "#21/#07 SS-Green Light Racing" = "team_s_"