Hello I'm trying to figure out problem 4 AT&T Annual report 2019 & 2018

1. What could explain the changes from one year to another for each account selected in number 2?Your answer explains the why it changed, not how much it changed.Your reasons must be supported by data provided in the company's annual report.

these are the options that I've chosen and need a better explanation how why it would change?

1. Equipment 2019 = 17,694, in 2018 18,411

2. Interest expense = 2019 (8,422), 2018 (7,957)

3. Depreciation and amortization=2019 28,217 and in 2018 28,430

Thanks in advance