The side lengths to get an area of 40 could be 8 and 5
Area = length x width
So if one side is 8 and the other is 5 then it will have to be the same on the opposite side of the rectangle
Perimeter = side + side + side+ side
So it is 8+8+5+5 = 16+10 = 26 feet
This is just one answer, there is more than one correct answer for this problem