Solution
= Solution
The <first law of thermodynamics>, with $\Delta Q$ defined as heat lost by the particle to the bath, is
$$
\Delta H=W-\Delta Q.
$$
Thus $W-\Delta H=\Delta Q$, and part d becomes the <local detailed balance> identity
$$
\boxed{\frac{\mathbb P_F}{\mathbb P_B}=e^{\beta\Delta Q}.}
$$
The logarithmic path-probability ratio is the bath's <entropy production> $\Delta S_{\rm bath}=\Delta Q/T$ in units of $k_B$.