7. In an equilateral triangle $ABC$ with side length 10, two squares (squares 甲 and 乙 overlap on one side, both have one side on $BC$, square 甲 has one vertex on $AB$, and square 乙 has one vertex on $AC$) are inscribed as shown in Figure 15. Find the minimum value of the sum of the areas of these two inscribed squares.
$$
\left.\frac{25}{2}(3-\sqrt{3})^{2}\right)
$$