SOLUTION: The perimeter of a rectangle is 420 inches. The width is 4 inches less than the length. What is the length of the rectangle?

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Question 42113: The perimeter of a rectangle is 420 inches. The width is 4 inches less than the length. What is the length of the rectangle?
Found 2 solutions by psbhowmick, tutorcecilia:
Answer by psbhowmick(878) About Me  (Show Source):
You can put this solution on YOUR website!
Let length = x inches.
Then, width = (x - 4) inches.
Thus perimeter = 2(Length + Width) = 2(x + (x - 4)) = 2(2x - 4) = 4(x - 2) inches.
But it is given that perimeter = 420 inches.
So 4(x - 2) = 420
or x - 2 = 420%2F4 = 105
or x = 105 + 2 = 107.

Hence, reqd. length is 107 inches.

Answer by tutorcecilia(2152) About Me  (Show Source):
You can put this solution on YOUR website!
The formula for the perimeter is:
Perimeter = 2(length + width)
P = 2(l+w)
.
Plug in the known and unknown values:
P = 420
Length = x
Width = (length-4)=(x-4)
.
420 = 2[x + (x - 4)]
.
Simplify and solve for x:
420 = 2(2x - 4)
420 = 4x - 8
420+8 = 4x -8 + 8
428 = 4x
428/4 = 4x/4
107=x
Plug-in x = 107 to check.
420 = 2(107 + (107-4))
420 = 2(107 + 103)
420 = 2(210)
420=420