Question 550080
"To solve for" usually means you isolate the variable on one side and everything else on the other side. Then you can substitute values or do other operations, depending on the given information.  However, in this case there is no additional given information.
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P = 4s
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I surmise that function calculates the perimeter of a square, where P = perimeter and 's' is the length of the sides. Showing the multiplication with an '*' sign.
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P = 4*s
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Divide both sides by 4 to isolate 's'.
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P/4 = (4*s)/4 
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The 4's cancel, leaving 's' alone.
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s = P/4
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Done.