Table:
0
A
B
C
D
1
Combined Pension Plan
2
Years Ended December 31,
3
2019
2018
2017
4
(Dollars in millions)
5
Change in benefit obligation
6
Benefit obligation at beginning of year
$11,594
13,064
13,244
7
Service cost
56
66
63
8
Interest cost
436
392
409
9
Plan amendments
(9)
—
—
10
Special termination benefits charge
6
15
—
11
Actuarial (gain) loss
1,249
(765)
586
12
Benefits paid from plan assets
(1,115)
(1,178)
(1,238)
13
Benefit obligation at end of year
$12,217
11,594
13,064

Questions and formulas:
Question: What is the total special termination benefits charge in 2018 and 2019?
Formula: B10+C10
Formula2: B10+C10
Level: Calculation
Question: What is the percentage change in interest cost in 2019 from 2018?
Formula: (B8-C8)/C8
Formula2: (B8-C8)/C8
Level: Calculation