So to find the answer you’ll need the areas. The rectangular gardens each are 18 times 15 which is 270 feet squared but there is 5 of those so it’ll be 5 times 270 which is 1350 feet squared. The city is 80 times 140 which is 11200. Now subtract 11200 and 1350 to get 9,850 squared feet which is the amount of square feet of park not used.