Jeff's Copy Shop bought a copier for $24,000 on January 1, 2018. Jeff estimated the useful life to be 3 years with salvage value of $9,000, and the straight-line method of depreciation will be used. On January 1, 2020, Jeff decides that the business will use the equipment until December 31, 2024, after which the salvage value will become $2,000. What is the revised depreciation expense for 2020? $3,000 $2,400 $2,800 $1,200