D is the correct answer I think
Answer:
<u> </u><u>For</u><u> </u><u>y</u><u> </u><u>:</u>
From pythogras theorem:

For the second largest inner triangle;

Equate (a) and (b):

solve the equation to get values of x, which will give you y
To begin with, you need to find the total number of pencils, which is 21.
Then you subtract 21 from 6 (red pencils) to find how many are not red.
The answer is B. 15 pencils are not red.
~Revilla03