I couldn't upload an image so here's a link to the question. Thanks
Since the area of the square is 8, each side of the square is sqrt(8).
Assuming that the triangle has sides that are the same lengths as the sides of the square, each side of the triangle is
Since a side of the triangle is sqrt(8) the diagonal of the square is sqrt(8).
To find the length of the side of the square, divide the length of the diagonal by sqrt(2).
sqrt(8) / sqrt(2) = 2.
Therefore, the area of the pink square is 2 x 2 = 4.