Can some please explain. I don't know how to get to the answer and why is it understated

Multiple Choice Question 66 Your answer is correct. Cullumber Company purchased equipment that cost $3045000 on January 1, 2017. The entire cost was recorded as an expense. The equipment had a 9-year life and a $121800 residual value. Cullumber uses the straight-line method to account for depreciation expense. The error was discovered on December 10, 2019 Cullum ber is subject to a 40% tax rate. Cullumber's net income for the year ended December 31, 2017, was understated by $1632120 $1827000 $2720200 $3045000 Click if you would like to Show Work for this question: Open Show Work