Nonlinear equations in one variable and systems of equations in two variables SAT question

Choice D is correct. To express $j$ in terms of $k$ and $m$, the given equation must be solved for $j$. Dividing each side of the given equation by $8$ yields  $j=\frac{k+15m}{8}$.

Choice A is incorrect. This is equivalent to $8j=k+120m$.

Choice B is incorrect. This is equivalent to $8j=8k+15m$.

Choice C is incorrect. This is equivalent to $\frac{j}{8}=k+15m$.