Answer:
There are 29 triangles when you count them all including non obvious ones.
The answer is C, you can tell because the b=-1, so that eliminates d, then you know the slope is positive because of the direction it goes, so that eliminates a. Then if you look at the slope, it goes up 3 over 1, so that makes the answer C.
Hope this helps
N - 7 = 9 if you want it written in equation form
I'm assuming you mean (a-b)^2 : (a+b)^2
a^2 + b^2 cancel out leaving
-2ab versus +2ab
Therefore (a+b)^2 is +4ab greater.