F2. mm b-mmdkmdkhew iii- rival-hll ill-ill.- e a

The answer's 8 - 10 square units. This is because if you add up the two triangles on the top left, that that makes a single cube. Also, it you take the triangle in the center and add it to a triangle on the bottom right, it makes another cube. The last two triangles can be added up to make more than one cube, so the answer is still 8 - 10 units.