The length of a rectangle is three times its width. If the perimeter of the rectangle is 40 in, find its length and width.

Question

i need help with these types of problems for math 

Answer 1

L= 3W

Perimeter = 2(l+w) = 40

 

2(3w+w) = 40

 

2*4w = 40

8w =40

w = 5

l = 3*5 = 15

Answer 2

Hi Mariana.

 

The perimeter of a rectangle = length + length + width + width, so

2L + 2W = 40"

 

But they also tell you that L = 3W since the length is 3 times the width.

 

If you substitute, you get 2(3W) + 2W = 40"  ...you can now solve for the width, and then use that to find the lenght.