SOLUTION: please SOLVE and CHECK this algebra problem : "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 235338: please SOLVE and CHECK this algebra problem : "the perimeter of a rectangle is 420 inches.The width is 4 inches less than the length.What is the length of the rectangle?"
Answer by Stitch(187) About Me  (Show Source):
You can put this solution on YOUR website!
The perimeter of a rectangle is equal to 2L + 2W
Equation 1: 2%2AL+%2B+2%2AW+=+420in
Equation 2: W+=+L+-+4in
Solution:
Plug L-4 into equation 1 for W
2%2AL+%2B+2%2AW+=+420in
2%2AL+%2B+2%2A%28L+-+4%29+=+420in rewrite the equation
2%2AL+%2B+2%2AL+-+8+=+420in Combine like terms
4%2AL+-+8+=+420in Add 8 to both sides
4%2AL+=+428in Divide both sides by 4
L+=+107in
The length of the rectangle is 107in.
Check your answer:
Plug 107 into equation 2 for L
W+=+L+-+4in
W+=+107+-+4in
W+=+103in
Now plug the answers for L and W into equation 1
2%2AL+%2B+2%2AW+=+420in
2%2A107+%2B+2%2A103+=+420in
214in+%2B+206in+=+420in
420in+=+420in