It seems you already have the result. What is it you want to compute, and based on what data?
There is no way to compute the dimension of a rectangle from its area. 40 square inches, you see, could be 1"x40" or 2"x20", or 4"x10", or . . . . . . but they would all be 40 square inches.
Area = length x width 40 = length x 4.5 length = 40/4.5 = 8.8888 meter
meow?
you have to treat it like a square then subtract the missing areas
Compute to the smallest fraction, reduce to the least number