If we use 3.14 as pi, the areas of these circles are 415.265 square units (I recommend rounding up to 415.27 unless it says otherwise).
Explanation:
To find the area of a circle, square the radius and multiply it by pi. To find the radius, we divide the diameter by 2 to get 11.5. Then, square 11.5 to get 132.25 and multiply by pi, or 3.14, to get 415.265, rounding up to 415.27 square units.