I assume the figure is like this



And the shaded area is this apple core: 



The rectangle is a square with side 9, so its area is 9² or 81 sq.ft.

The two semicircles make 1 complete circle, with diameter 9, which
means its radius is  and the area is pr²
or p or p.

So if we subtract the circle's area from the square's area, we get

81 - p =

81 - ×3.14

81 - 20.25×3.14

81 - 63.585

17.415 sq.ft.

Edwin