SOLUTION: a rectangles length is four times it's width, and the perimeter of the rectangle is 30. what is the length and width of this rectangle

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Question 774755: a rectangles length is four times it's width, and the perimeter of the rectangle is 30. what is the length and width of this rectangle
Answer by ananna(1) About Me  (Show Source):
You can put this solution on YOUR website!
L=4W This is another way of saying that the length (L) is four times the width (W).
P=2%28L%2BW%29 This is the formula for the perimeter of a rectangle (P is the perimeter).
30=2%28L%2BW%29 Since we know the perimeter is 30, we can plug in 30 for P.
30=2%284W%2BW%29 Now we can plug in 4W for L, since L=4W.
30=2%285W%29 We can combine 4W and W to get 5W.
%2830%29%2F%282%29=%282%285W%29%29%2F%282%29 To isolate W, we can divide both sides by 2.
%2815%29%2F%285%29=%285W%29%2F%285%29 To further isolate W, divide both sides by 5.
3=W Now you know what W is.
L=4%2A3 Plug in 3 for W to calculate L, since L=4W.
L=12 Now you know both W and L.
So the length is 12 and the width is 3. Don't forget to include the units, like inches, feet, meters, etc.

And that's all there is to it!!!