SOLUTION: A square animal pen and a pen shaped like an equilateral triangle have equal perimeters. Find the length of the sides of each pen if the sides of the triangular pen are fifteen les

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Question 126053This question is from textbook
: A square animal pen and a pen shaped like an equilateral triangle have equal perimeters. Find the length of the sides of each pen if the sides of the triangular pen are fifteen less than twice a side of the square pen.
What I know: P=4s and P=3a, a=2s-15. That's all. I don't know how to use that information, if it's useful in solving the problem, or how to get started on the problem. I've tried drawing pictures and solving for various things, I'm seriously stumped and any help would be GREATLY appreciated. Thank you so much. This question is from textbook

Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
good so far __ the perimeters are EQUAL __ P=P __ 3a=4s

substituting __ 3(2s-15)=4s __ 6s-45=4s __ 2s=45