Table:
0
A
B
C
D
1
Years Ended December 31,
2
2019
2018
2017
3
(Dollars in millions)
4
Balance at beginning of year
$190
115
95
5
Accretion expense
11
10
6
6
Liabilities assumed in acquisition of Level 3(1)
—
58
45
7
Liabilities settled
(14)
(14)
(3)
8
Liabilities transferred to Cyxtera
—
—
(20)
9
Change in estimate
10
21
(8)
10
Balance at end of year
$197
190
115

Questions and formulas:
Question: What is the change in balance at end of year in 2019 from 2018?
Formula: B10-C10
Formula2: B10-C10
Level: Calculation
Question: What is the average accretion expense across 2017, 2018 and 2019?
Formula: (B5+C5+D5)/3
Formula2: (B5+C5+D5)/3
Level: Calculation