Coefficientwise quotient of a polynomial ring
= Coefficientwise quotient of a polynomial ring
For an ideal $I$ of a commutative ring $R$, reducing coefficients modulo $I$ is a surjection $R[X]\to(R/I)[X]$ with kernel $I[X]$. Hence
$$
R[X]/I[X]\cong(R/I)[X].
$$