how to find the length of a rectangle with the perimeter 42 feet and the length is twice the width

Question

P=2W+2L length width perimeter 

Answer 1

Hello Siandra,

 

So I see that you got the formula, P=2W+2L. You know that the perimeter is 42 ft, so you can substitute this in:

 

42 = 2W + 2L

 

This is still difficult to solve because there are two different variables! Thankfully, we have another given information: length is twice the width. In other words, length equals 2 times width (L = 2W, or W= 1/2 L)

 

Now, lets substitute this information into the equation so that we only have L as our variable:

 

42 = 2(1/2 L) + 2L

 

This can be further simplified to:

 

42 = L + 2L --> 42 = 3L --> L = 14

 

The answer is 14 ft!

 

 

I hope this helps,

 

Megan

Answer 2

x= width of the rectangle

2x=length of the rectangle

 

so:

P=2L+2W

P=2(2x)+2x

42= 4x+2x

42=6x

x=7

2x=14