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Answer:

Step-by-step explanation:
Expression for the rectangular area and perimeter are, respectively:


After some algebraic manipulation, area expression can be reduce to an one-variable form:


The first derivative of the previous equation is:

Let the expression be equalized to zero:


The second derivative is:

According to the Second Derivative Test, the critical value found in previous steps is a maximum. Then:

The maximum area is:


To find the solution
-4x>36
divide both sides by -4
(REMEMBER WHEN YOU DIVIDE BY A NEGATIVE, THE SIGN FLIPS OVER)
x < -36/4
simplified
x < -9
Hope this helps :)
Yes, I would say so, or a right triangle.
I'm Sorry I not good when it comes to tax but it might be around 21.30 maybe I most likely am wrong