A7. Let $A, B, C$, and $D$ be squares. The perimeter of square $A$ is $16 \mathrm{~cm}$, and the perimeter of square $B$ is $24 \mathrm{~cm}$. What is the sum of the areas of all the squares?
(A) $350 \mathrm{~cm}^{2}$
(B) $378 \mathrm{~cm}^{2}$
(C) $408 \mathrm{~cm}^{2}$
(D) $430 \mathrm{~cm}^{2}$
(E) $510 \mathrm{~cm}^{2}$

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A7. The side of square $A$ is $16 \mathrm{~cm} : 4 = 4 \mathrm{~cm}$, the side of square $B$ is $24 \mathrm{~cm} : 4 = 6 \mathrm{~cm}$. The side of square $C$ is $10 \mathrm{~cm}$, and the side of square $D$ is $16 \mathrm{~cm}$. The sum of the areas of all squares is $S_{A} + S_{B} + S_{C} + S_{D} = 16 \mathrm{~cm}^{2} + 36 \mathrm{~cm}^{2} + 100 \mathrm{~cm}^{2} + 256 \mathrm{~cm}^{2} = 408 \mathrm{~cm}^{2}$.