Actuary and trustee reports indicate the following changes in the PBO and plan assets of Douglas-Roberts Industries during 2021: \begin{tabular}{|l|r|r|} \hline \multicolumn{2}{|c|}{ Pension Expense } \\ \hline Service cost & & $0 \\ \hline Interest cost & & 42 \\ \hline Expected return on plan assets & (60) \\ \hline Amortization of net loss & 2 \\ \hline Amortization of prior service cost & & 4 \\ \hline & & \\ \hline Pension expense & $ & 68 \\ \hline \end{tabular}