SOLUTION: Can you please explain this equation to me. The length of a rectangle is 3 times the width. The perimeter is 96 cm. Find the width and length I want to know how to work it ou

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Question 671997: Can you please explain this equation to me.
The length of a rectangle is 3 times the width. The perimeter is 96 cm. Find the width and length
I want to know how to work it out properly.
Thank you
Sorry if this is the wrong category I don't know which one I should of put it on.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +L+ = the length of the rectangle
Let +W+ = the width of the rectangle
given:
(1) +L+=+3W+
The formula for perimeter of a rectangle is
(2) +P+=+2W+%2B+2L+
Substitute (1) into (2)
(2) +P+=+2W+%2B+2%2A%283W%29+
You are given +P+=+96+ cm
(2) +96+=+2W+%2B+6W+
(2) +8W+=+96+
(2) +W+=+12+
and, since
(1) +L+=+3W+
(1) +L+=+3%2A12+
(1) +L+=+36+
The length is 36 cm and the width is 12 cm
check:
(2) +P+=+2W+%2B+2L+
(2) +P+=+2%2A12+%2B+2%2A36+
(2) +P+=+24+%2B+72+
(2) +P+=+96+ cm
OK