On the sheet, it's not even asking you for the dimensions.
It's just asking you to set up the equation that you would use
to find the dimensions. That's a great way to do it, because
nobody actually needs the answers, the whole thing is only
meant to help you learn HOW to find them.
==========================================
Call the width of the window 'W' .
We know that the length is 5 feet more than the width, so the length is (W + 5).
The area is (length times width).
Area = (W + 5) times (W).
36 = (W + 5) W
36 = W² + 5W
Subtract 36 from each side:
W² + 5W - 36 = 0
That's choice-4 .