To find circumference, you must multiply the diameter by pi, (roughly 3.14)
To find area, you can use the formula A=pi (radius) squared
Radius is half of diameter
For the large pizza, the circumference would be about 50.265. You can round this to ~50 inches.
The area would be about 201.06 inches. You can round this to 201 inches
For the medium pizza, the circumference would be about 37.69 inches. The area would be about 113.09 inches squared.