With a 40-ft perimeter, there an infinite number of possibilities for the length and with. The only thing we know for sure is that the sum of (length + width) is 20-ft.
The field could be . . .
1' by 40' 2' by 20' 3' by 13-1/3 ' 4' by 10' 5' by 8' 6' by 6-2/3 '
