Hey!
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Steps To Solve:
Since this is a square all sides need to be equal.
3x = 5x - 8
~Subtract 5x to both sides
5x - 3x = 5x - 8 - 5x
~Simplify
2x = 8
~Divide 2 to both sides
2x/2 = 8/2
~Simplify
x = 4
So now we know all the sides are worth 4.
~Find perimeter
4 + 4 + 4 + 4 = 16
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Answer:
The perimeter is 16!
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Hope This Helped! Good Luck!