Answer
$x=120~yards$
$y=53~1/3~yards=53.33~yards$
Work Step by Step
The results of part (d) lead us to a rectangle that is almost a square. In fact, if we had evaluated the exact dimensions that would give us the maximum area, we would have found a square ($86.67~yards\times86.67~yards$)
Of course, the NFL playing field is not a square.
