Table: australian_drivers_championship_1989
Columns: circuit
city_state
date
winner
team

Question: What is City / State, when Winner is "Rohan Onslow", and when Circuit is "Oran Park Raceway"?
SQL: SELECT "city_state" FROM australian_drivers_championship_1989 WHERE "winner" = 'rohan onslow' AND "circuit" = 'oran park raceway'

Question: What is Winner, when City / State is "Mallala , South Australia", and when Team is "Elfin Sports Cars"?
SQL: SELECT "winner" FROM australian_drivers_championship_1989 WHERE "city_state" = 'mallala , south australia' AND "team" = 'elfin sports cars'

Question: What is Circuit, when Team is "R.J.MacArthur Onslow", and when City / State is "Sydney , New South Wales"?
SQL: SELECT "circuit" FROM australian_drivers_championship_1989 WHERE "team" = 'r.j.macarthur onslow' AND "city_state" = 'sydney , new south wales'

Question: What is Winner, when Team is "R.J.MacArthur Onslow", and when Circuit is "Oran Park Raceway"?
SQL: SELECT "winner" FROM australian_drivers_championship_1989 WHERE "team" = 'r.j.macarthur onslow' AND "circuit" = 'oran park raceway'

Question: What is Date, when City / State is "Mallala , South Australia", and when Team is "R.J.MacArthur Onslow"?
SQL: SELECT "date" FROM australian_drivers_championship_1989 WHERE "city_state" = 'mallala , south australia' AND "team" = 'r.j.macarthur onslow'

Question: What is Winner, when Date is "20 August"?
SQL: SELECT "winner" FROM australian_drivers_championship_1989 WHERE "date" = '20 august'