Question

The perimeter of a square newspaper ad is 40 centimeters. How long is each side?

Answer 1

The answer is:  "10 cm" .
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Method 1)
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2L + 2w = 40 ;  Since the formula for perimeter of a rectangle (Note: a square is a rectangle) is:

                         P = 2L + 2w ;  Note:  L = length; w = width; P = perimeter;
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 Factor out a "2":
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" 2L + 2w = 40" ;

2 (L+ w) = 40;

Divide each side of the question by "2" ;
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         [2 (L + w)] / 2  = 40 / 2 ;
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 to get:  (L + w) = 20 ;

Note:  this "rectangle is a square" ; so L= w".
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20 /2 = 10 ;

L + w = 10 + 10 = 20.

This is a square, so each side of the square is the same length.

Each side is:  10 cm .
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Method 2)
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We are given: The perimeter (sum of the lengths of all sides) of a square is "40 cm."  Since a square has 4 sides of equal length:
     Each side is:  40 cm / 4 = 10 cm.
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