Answer:
C
Step-by-step explanation:
slope intercept is y=mx+b
The y-intercept is at 2 so b=2.
The slope is rise/run, equaling -3
so y= -3x+2
If you're only counting the smallest triangles, then 8.
If you're counting all possible triangles including triangles made of other triangles, then 16. Each diagonal gives 2, the combined diagonals give 4, and the unit triangles give 8 for a total of 2 + 2 + 4 + 8 = 16.

total number of students : 1240
(3*15)+(17*15)=45+255=300
the final answer is 300
or 20 fifteens