1. Why use layers in Illustrator?

Layers provide a way to manage each individual piece of your artwork. Say you notice you made an error on a previous layer, with the practice of using various layer, you don't have to undo everything that you have already worked on, but instead fix the mistake on the specific layer

Explanation:

perimeter = 2l +2w, divide total perimeter by 2 for total length of 1 side and 1 width

172/2 = 86 (  total for 1 side and 1 width)

86-24 = 62 (since length is 24 ft longer subtract 24 then divide by 2 for width)

62/2 = 31

width = 31 feet

length = 31 +24 = 55 feet

check: 31*2 = 62, 55*2 = 110,  110+62 = 172