<PRE><B>Question 823231</B>
Perimeter = 4*(Side length) 


P = 4*s


20n+10 = 4*(4n+7)


20n+10=16n+28


20n=16n+28-10


20n-16n=28-10


4n=28-10


4n=18


n=(18)/(4)


n=9/2


n = 4.5


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Side length


s = 4n + 7


s = 4*4.5 + 7


s = 25


So the side length is 25 units.
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