90.32 square inches
Explanation
Step 1
the area of the circle is given by:
[tex]\text{Area}=\frac{\pi}{4}\cdot diameter^2[/tex]Step 2
find the areas
birthday cake
[tex]\begin{gathered} \text{Area}_b=\frac{\pi}{4}\cdot9^2 \\ \text{Area}_b=\frac{81\pi}{4} \\ \text{Area}_b=\frac{254.46}{4} \\ \text{Area}_b=63.61\text{ square inches} \end{gathered}[/tex]Now, the wedding cake
[tex]\begin{gathered} \text{Area}_w=\frac{\pi}{4}\cdot14^2 \\ \text{Area}_w=\frac{\pi}{4}\cdot196\text{ square inches} \\ \text{Area}_w=49\cdot\pi\text{ square inches} \\ \text{Area}_w=153.93\text{ square inches} \end{gathered}[/tex]Step 3
finally, find the difference
[tex]\begin{gathered} \text{difference}=153.93\text{ square inches-63.61 inches} \\ \text{difference}=90.32 \end{gathered}[/tex]so, the answer is 90.32 square inches
