So the formula for the area of the circle is [tex] A=\pi r^2[/tex] . To find the radius is divide the diameters by 2, which in this case its 2 and 3. Now we can find the areas.
[tex]A= \pi 2^2 \\ A=4 \pi [/tex]
[tex]A= \pi3^2 \\ A=9 \pi [/tex]
Now just subtract the areas: [tex]9 \pi -4 \pi =5 \pi [/tex]
The difference in areas is 5 pi, or 15.71.