Algebra

Out of the entire equation (which is quite messy), we only need to pay attention to the $x$ term. There are two possible ways to get a term that has degree one in this equation: $1 \cdot -23x$ and $x \cdot 14$. Therefore, the coefficient of $x$ is the sum of those two terms, which is $-9x$.

Feel free to correct me if I'm wrong! :D