On January 1, 2016, Gibson Corporation entered into a four-year operating lease. The payments were?

... as follows: $24,000 for 2016, $17,000 for 2017, $15,500 for 2018, and $13,500 for 2019. What is the correct amount of lease expense for 2017?

My Answer $17,000.
Corrent Answer $17,500.
$24,000.
$20,500.

2016 $24,000
2017 17,000
2018 15,500
2019 13,500

Total
$70,000

$70,000 / 4 = $17,500

What concept should I be looking for in my textbook to explain why that was the correct answer. I have asked my professor she told me that the question was complicated