A=10, B=11, C=12, etc.
Now, the "only" thing that remains to do is solving the above equation.
While making this problem I only made sure it has a solution. I didn't try to solve it myself and I didn't know it will end up with such "convoluted" polynomial. Sorry to everyone who tried to solve it... m(_ _)m
I think the best way to approach it is using the rational root theorem since we know that . Moreover we can deduce that
since there is
and
.
After you succesfully solve it, you should get the answer .