Table:
text: 1989 Australian Drivers' Championship
Race calendar
Race calendar
Circuit City_State Date_ Winner Team
Mallala Motor Sport Park Mallala , South Australia 7 May Mark McLaughlin Elfin Sports Cars
Mallala Motor Sport Park Mallala , South Australia 7 May Rohan Onslow R.J.Macarthur Onslow
Winton Motor Raceway Benalla , Victoria 4 June Rohan Onslow R.J.Macarthur Onslow
Winton Motor Raceway Benalla , Victoria 4 June John Briggs John Briggs
Oran Park Raceway Sydney , New South Wales 4 August Rohan Onslow R.J.Macarthur Onslow
Oran Park Raceway Sydney , New South Wales 4 August Rohan Onslow R.J.Macarthur Onslow
Amaroo Park Sydney , New South Wales 20 August Neil Crompton Boylan Racing

text: 1989 Australian Drivers' Championship
Race calendar
Race calendar
Circuit City_State Date_ Winner Team
Amaroo Park Sydney , New South Wales 20 August Simon Kane Clive Kane Photography
Sandown International Raceway Melbourne , Victoria 9 October Sam Astuti Cascone Corporation
Sandown International Raceway Melbourne , Victoria 9 October Neil Crompton Boylan Racing

Question: For the Australian Drivers' Championship 1989 Circuit, what if Team is "RJMacArthur Onslow" and if City/State is "Sydney, New South Wales"?

Question: What is winner when the date is "20th August" for the 1989 Australian Drivers' Championship?