The Kollar Company has a defined benefit pension plan. Pension information concerning the fiscal years $2024$ and $2025$ are presented below $($$ in millions$)$:

Information Provided by Pension Plan Actuary:

a$.$ Projected benefit obligation as of December $31,2023=$ $$3,200.$

b$.$ Prior service cost from plan amendment on January $2,2024=$ $$600($straight$-$line amortization for $10-$year average remaining service period$).$

c$.$ Service cost for $2024=$ $$640.$

d$.$ Service cost for $2025=$ $$690.$

e$.$ Discount rate used by actuary on projected benefit obligation for $2024$ and $2025=10\%.$

f$.$ Payments to retirees in $2024=$ $$500.$

g$.$ Payments to retirees in $2025=$ $$570.$

h$.$ No changes in actuarial assumptions or estimates.

i$.$ Net gain$$AOCI on January $1,2024=$ $$370.$

j$.$ Net gains and losses are amortized for $10$ years in $2024$ and $2025.$

Information Provided by Pension Fund Trustee:

a$.$ Plan asset balance at fair value on January $1,2024=$ $$2,300.$

b$.2024$ contributions $=$ $$660.$

c$.2025$ contributions $=$ $$710.$

d$.$ Expected long$-$term rate of return on plan assets $=12\%.$

e$.2024$ actual return on plan assets $=$ $$210.$

f$.2025$ actual return on plan assets $=$ $$260.$

Required:

$1.$ Calculate pension expense for $2024$ and $2025.$

$2.$ Prepare the journal entries for $2024$ and $2025$ to record pension expense.

$3.$ Prepare the journal entries for $2024$ and $2025$ to record any gains and losses and new prior service cost.

$4.$ Prepare the journal entries for $2024$ and $2025$ to record $($a$)$ the cash contribution to plan assets and $($b$)$ the benefit payments to retirees.