1) 9
2) The area of the two "triangles" is the same. the two big triangles are not actually triangles, they just look like it. the slope of the hypotenuse on the red and blue small triangles is different. the red triangle is 2/5 and the blue triangle is slightly smaller with 3/8. because the two small triangles have different angles and the large triangles are not actually real triangles, the hole appears when the shapes are rearranged.
3) O (letter o)
