If the diameter is given in a problem, area is computed as
A = (π/4) × D2 where π is equal to 3.14
If D (diameter) of one circular table is 6 ft its Area is 28 sq ft.
If D of another circular is 8 ft its Area is 50 sq ft.
The difference between the areas of the two tables is, therefore (50-28) or 22 sq. ft.