The commutative property lets you swap the order of operands. It would let Ed write
... 3×6 = 6×3
or
... 2×9 = 9×2
I don't see how this shows both arrays have 18 tiles. I would say Ed is not correct.
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On the other hand, Ed could use the associative property to show that ...
... 3×(3×2) = (3×3)×2
which is to say
... 3×6 = 9×2
This seems to be what Ed is trying to show.
