SOLUTION: The length of the rectangle is three times it's width and the perimeter of the rectangle is 80 cm. What is the width of the rectangle ?

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Question 829279: The length of the rectangle is three times it's width and the perimeter of the rectangle is 80 cm. What is the width of the rectangle ?
Found 2 solutions by TimothyLamb, erica65404:
Answer by TimothyLamb(4379) About Me  (Show Source):
You can put this solution on YOUR website!
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x = 3y
2x + 2y = 80
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put the system of linear equations into standard form:
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x - 3y = 0
2x + 2y = 80
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copy and paste the above linear system in standard form into this matrix-method solver:
https://sooeet.com/math/system-of-linear-equations-solver.php
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solution:
x = length = 30 cm
y = width = 10 cm
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Answer by erica65404(394) About Me  (Show Source):
You can put this solution on YOUR website!
Start by making an equation for perimeter.
l%2Bl%2Bw%2Bw=80
now we know that the length is equal to 3 times the width, l=3w, and that width just equals width, w=w.
now since i=3w, we can replace all l's with 3w.
%283w%29%2B%283w%29%2Bw%2Bw=80
8w=80
w=10
since w is the width, the width is 10 cm.
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