Connor S.

asked • 01/30/18

The length of a rectangle is 30 inches and the width is w inches. The perimeter of th rectangle is 240 inches. Find the width.

please help me solve this.

1 Expert Answer

By:

Al P. answered • 01/30/18

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Perimeter, P = 2L + 2W
 
In units of inches:
240 = 2(30) + 2W
 
Can you solve for W?       
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Al P.

I hope you see how  P = 2L + 2W  (in going around the rectangle once, you will encounter the width twice and the length twice).
 
240 = 2(30) + 2W
240 = 60 + 2W    (carried out the 2(30))
240-60 = 60 + 2W - 60    (subtract 60 from both sides, maintaining the equality)
180 = 2W             (the 60's on the right hand side combine to 0)
Now we can just divide both sides by 2 to get W by itself (one W gives us the answer)
180/2 = 2W/2
90 = W
----
So the width is 90in.   (Usually the longer dimension is called the 'length' and the width is the shorter dimension, but if that's how the problem is worded then so be it).  
 
Check:  90*2 + 30*2 = 180 + 60 = 240 (ok, two lengths + two widths equals the given perimeter)  
 
I will tell you knowing mathematics (especially the basics, like this problem) will help you a lot throughout your life.
It is worth the effort to learn it / improve your skills.  
 
 
 
 
 
 
 
 
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01/30/18

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