What are the length and width?

Question

The length of a rectangle is twice as great as it's width. When both width and length are increased by 5 inches, the new rectangle has a perimeter of 80 inches. Write an equation to find the length and width of the original rectangle.

Answer 1

The length of a rectangle is twice as great as it's width:

 

L = 2W

 

When both width and length are increased by 5 inches, the new rectangle has a perimeter of 80 inches

 

2(L+5)+ 2(W+5) = 80

 

Substitute 2W for L:

 

2(2W+5) + 2(W+5) = 80

 

4W + 10 + 2W + 10 = 80

 

6W + 20 = 80

 

6W = 60

 

W = 10 inches

 

L = 2W = 2*10 = 20 inches