On July 1, 2018, Runners, Inc., purchases a truck for $36,000 with a useful life of 60,000 miles. The residual value is $6,000. Actual miles driven, by year, are: 2018 (5,000); 2019 (10,000); 2020 (20,000); 2021 (25,000); 2022 (30,000). What is the book value of the truck on December 31, 2020? $18,500 $26,000 $12,500 $33,500