CGT on shares, page-62

I'm just new at this (working through my first tax return involving stock investments) and was looking through the threads for general guidance on some things when I saw this post...
And maybe I'm just having a moment, but where are you getting the $6k profit from?

I personally interpreted it as: Cost price = $10k and sell price = $10k, therefore net gains = $0.
When they sell their remaining 75000 shares, then they will have to declare the net gains as the total amount and pay the appropriate amount of tax on that amount.
Please correct me if I'm wrong, as I honestly want to know if I'm not understanding things correctly.
Cheers

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