Answer:
4212 square feet.
Explanation:
If the blueprint's scale is 1 inch : 9 feet.
Square both sides
(1in)² = (9ft)²
1in² = 81ft²
Given the gym's area as 52 square inches, hence;
52in² = x
Divide both expressions
1/52 = 81/x
x = 52 * 81
x = 4212ft²
Hence the area of the actual gym is 4212 square feet.