Step-by-step explanation:
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Surely not;
5a+a-9b-6b
6a-15b
So,
5a-9b+a-6b=6a-15b
It's not equal to 6a-15
No these envelopes aren’t similar. If you add up the sides they both don’t equal the same. Making them non congruent.
The area would be 9 because the perimeter of the regular quadrilateral would be 3 and if you multiply 3 by 3 you have 9.