Asquare frame has a perimeter of (16x - 20) feet. write an expression that represents the side length of the picture frame (in feet).

Perimeter is all of lengths of the sides added up. We know a square has four sides, all the same length. Therefore each side must be exactly ¼ of the perimiter.
So that's (16x-20)÷4
We can simplify that, by dividing both 16x and 20 by 4 to get (4x-5)
So the length of one side is (4x-5)ft

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