question: What is Circuit, when Team is "R.J.MacArthur Onslow", and when City / State is "Sydney , New South Wales"?
answer: SELECT circuit FROM table_name_54 WHERE team = "r.j.macarthur onslow" AND city___state = "sydney , new south wales"
context: CREATE TABLE table_name_54 (circuit VARCHAR, team VARCHAR, city___state VARCHAR)