This question stumped some of the smartest maths students in Australia, and there's no way I would have solved it in an exam! Can you figure it out?

Syndey Morney Herald and video solution
https://www.smh.com.au/educati....on/the-state-s-top-m

Official test and solutions available at
https://educationstandards.nsw.....edu.au/wps/portal/n

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