Complex sentence: With 3,843 athletes taking part in the 18 sports on the programme, the Games were the second largest sporting event ever held in Australia, and utilized the same facilities as the largest, the 2000 Summer Olympics, which had concluded on 1 October.
Split into simpler sentences: With 3,843 athletes taking part in the 18 sports on the programme, the Games were the second largest sporting event ever held in Australia. The location and facilities were shared with the largest event, the 2000 Summer Olympics, which had concluded on 1 October.