Jeffrey K. answered • 08/17/20

Together, we build an iron base in mathematics and physics

Hi Iryna:

If you draw a diagram, you will see this is a very easy problem.

Let the side of the square be x feet.

Then, the total area of the square minus the area occupied by the building is 15,300 ft^{2}.

That is: x^{2} - (80 . 20) = 15300

=> x^{2} - 1,600 = 15,300

x^{2} = 15,300 + 1,600

x^{2} = 16,900

x - √16.900 = 130 ft

That's all!