I just had the question and the correct answer is 36.
Ok i know that 6x divided by 42 would be 6 so were left with y=3. Do you know what the next step is?
Option A:
is the complete factorization of the polynomial 
Explanation:
The polynomial is 
Now, we shall find the complete factorization of the polynomial.
Let us group the common terms, we have,

Taking out the common terms,

Factor out
from both the terms, we have,

The term
can be factored as
and 
Thus, the roots are
and 
These roots can be written as 
Thus, the complete factorization of the polynomial is 