Circular garden in the middle of a square yard. the radius of the circle is 4x. the side length of the yard is 20x. what is the area of the part of the yard that is not covered by the circle ?

-- The area of the entire yard, before the garden was planted, was

             (side)²  =  (20x)²  =  400 x² .

-- The area of the circle where garden was put in is

             pi R²  =  (pi) · (4x)²  =  16 pi x² .

--  The remaining area of the yard ... the part not covered by
the circular garden ... is

           (400x²) - (16pi x²)  =  x² (400 - 16pi)

                                           =           349.7 x²    square units.