The perimeter of a square is 80 minus 64 y units. Which expression can be used to show the side length of one side of the square?

A square has four equal sides, so divide its perimeter by 4: (80 − 64y) ÷ 4 = 20 − 16y. Therefore, the side length is 20 − 16y units, shown by choice C. The other expressions either do not divide the perimeter by 4 or omit the variable y from the side length.

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