Complex sentence: The Western Australian Oaks is a Perth Racing Group 3 Thoroughbred horse race for three year old fillies at set weights run over 2400 metres, held at Ascot Racecourse in Perth, Australia each year in April.
Split into simpler sentences: The Western Australian Oaks is a Perth Racing Group 3 Thoroughbred horse race for three year old fillies at set weights held over 2400 metres. It is run at Ascot Racecourse in Perth, Western Australia each year in April.