CREATE TABLE table_name_20 (city___state VARCHAR, winner VARCHAR, circuit VARCHAR)

What is City / State, when Winner is 'Rohan Onslow', and when Circuit is 'Oran Park Raceway'?
SELECT city___state FROM table_name_20 WHERE winner = "rohan onslow" AND circuit = "oran park raceway"
SELECT "city___state" FROM "table_name_20" WHERE "circuit" = "oran park raceway" AND "rohan onslow" = "winner"