Catriona Agg Rectangle Puzzle

I love Catriona's puzzles, but especially those with a degree of freedom. Adjust A, B and E as you like. Why does the answer stay the same?[br][br]Original on [url=https://bsky.app/profile/catrionaagg.bsky.social/post/3lt7mbgldxs2s]BlueSky[/url].

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