A5. Mija and Maja had to cut out an equilateral triangle from paper for their homework. The side of Mija's triangle is $5 \mathrm{~cm}$ long, and the side of Maja's triangle is $10 \mathrm{~cm}$. How many times larger is the area of Maja's triangle compared to the area of Mija's triangle?
(A) 2 times
(B) $\sqrt{3}$ times
(C) 3 times
(D) 4 times
(E) 5 times
A5. We calculate the areas of both equilateral triangles. If $a_{1}=5 \mathrm{~cm}$, then $S_{1}=\frac{25 \sqrt{3}}{4} \mathrm{~cm}^{2}$. If $a_{2}=10 \mathrm{~cm}$, then $S_{2}=\frac{100 \sqrt{3}}{4} \mathrm{~cm}^{2}$. The area $S_{2}$ is 4 times larger than the area $S_{1}$.