perimeter of any figure is all its sides summed up
for a rectangle, with two equal pairs, that means, length + length + width + width or 2length + 2width, or 2(length + width)
but we know the length is 7/5 the width
width = w
perimeter = P
[tex]\bf P=2\left(\frac{7}{5}w +w \right)\qquad P=240\implies 240=2\left(\frac{7}{5}w +w \right)
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120=\frac{7}{5}w +w\impliedby \textit{let's multiply both sides by 5}
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600=7w+5w\implies 600=12w\implies \cfrac{600}{12}=w[/tex]
and the length is 7/5 of that
