LN=8 because every time there is a midpoint you have to divide it in half. So 64,32,16,8
3 reds in the 10 remaining cards
so that is 30% are red
The answer is C.
You need you use Pythagoras theorem 2 times to have 2 equations with the same sides i.e. for example a2 + b2 = 81 and a2 - b2 = 9.
You can do it as you have different triangles but with the same sides.