First off, we need to know the area of a circle: pi*radius^2.
Now, we need to find the radius of each circle: Since the diameters are 14 and 10 respectively. Their radii are 7 and 5 respectively.
Now, we must find the area of each circle
14-in diameter circle: pi*7^2=153.94
10-in diameter circle: pi*5^2=78.54
Now, we must do a ratio: We will do the area of the 14-in diameter circle over the 10-in one. 153.94/78.54=1.96. So, the 14 in. diameter pizza is nearly twice as large as the 10 in. one.
Hope this helps.