You can
put this solution on YOUR website!A verbal expression?
There are two whole numbers involved, so let's call them a and b.
We will say that a>b.
The length of the rectangle is a+b.
The width of the rectangle is a-b.
The area of the rectangle is

Maybe the expected answer is
"The area of the rectangle is the difference between two perfect squares", or
"The area of the rectangle is numerically equal to the difference between two perfect squares," or some variation of that theme.