Probability distribution of $Y$ when $Y=\frac{a}{b+X}$, where $a,b>0$ and $\Pr(b+X\ne{0})=1$, $X\sim\mathcal{N}(0,\sigma^2)$

Question

How do I solve for the probability distribution of $Y$ when $Y=\frac{a}{b+X}$, where $a,b>0$ and $\Pr(b+X\ne{0})=1$, $X\sim\mathcal{N}(0,\sigma^2)$?