The perimeter of a rectangle is 42 feet. Find the dimensions if the length is fifteen feet shorter than three times the width (w). Choose the correct answer for the length.
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Step-by-step explanation:
perimeter is 2 times length plus 2 times width
let the length be x and the width be y
then x-3y=1, so x=3y+1
plug this into the perimeter formula
2x+2y=2(3y+1)+2y=6y+2+2y=8y+2
we know this equals 42, so set them equal and solve for y
8y+2=42
8y=40
y=5
solve for x
x=3y+1=3(5)+1=16
the rectangle is 5 ft by 16 ft