White space alignment

Hi, can you please have a short look on the attached picture, is there maybe some option in Alignment menu which makes equal white space between the three rectangles, but which is the same width between of the side borders too?

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So my target would be around this one which is below, I assumed that the "Distribute equi-spaced" position would give this but that seems does not. Actually my technique is to count the pixels, or maybe using some temporary rectangle with a certain width and moving the objects with Snap to objects. But that is not some too fast method
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Place two thin vertical lines to the left and right edges of your large back rectangle.
Select the two lines, three boxes and back rectangle and Distribute equi-spaced against the bounds of the back object (here, rectangle).
Delete the tow vertical lines.

Acorn

That is very clever like that, thanks for your advice it really works fast

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I liked solving it - it took longer to explain than invent.
I am sure there are better approaches and I hope people will share.

Acorn