Answer:
72 feet
Step-by-step explanation:
We first need to find the perimeter of yard, then, we find 2/5 of the perimeter to find the length of chain link that they will need.
The yard is rectangular and it has dimensions 40 feet long and 50 feet wide.
The perimeter of a rectangle is given as:
P = 2(L + W)
where L = length
W = width
Therefore, the perimeter of the yard is:
P = 2(40 + 50)
P = 2(90) = 180 feet
The length of chain link that they will need is therefore:
2/5 * 180 = 72 feet
They need 72 feet of chain link.