Actuary and trustee reports indicate the following changes in the PBO and plan assets of Richmond Industries during 2021 (\$ in millions): PBO, 1/1/2021 \$600 Plan assets, 1/1/2021 \$400 Prior service cost at January 1, 2021, from plan amendment at the beginning of 2018 (amortization: $4 millions per year) Net loss-c-AOCl at January 1, 2021$80 million (2021 amortization: \$1millions) Average remaining service life of the active employee group 20 years What is the plan assets balance at the end of 2021