SOLUTION: the length of a rectangle is 4cm less than twice its width.it's perimeter is 40cm.find it's length and width.

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Question 723055: the length of a rectangle is 4cm less than twice its width.it's perimeter is 40cm.find it's length and width.
Answer by 119078(26) About Me  (Show Source):
You can put this solution on YOUR website!
Write down and draw what you know to start.
Now it may seem tricky but "4cm less than twice its width" is very easy. Just brake it up into parts. The ending say 2 its width so 2w, then 4 cm less than which is -4. Put it all together and you have 2w-4=length.
Length=2w-4
Width=?
Perimeter=40cm
Now you need to plug in the variables into the perimeter formula.
P=2%28l%29%2B2%28w%29
40=2%282w-4%29%2B2%28w%29
Distribute 2 into 2w-4
40=4w-8%2B2w
Add like terms.
40=6w-8
Add 8 to both sides.
%2840%2B8%29=6w%28-8%2B8%29
48=6w
Divide 6 to both sides.
%2848%2F6%29=%286w%2F6%29
8=w
Find length
l=2%288%29-4
l=16-4
l=12
Answer
8=w & l=12
I hope this step by step helps you out :)!