Cullumber Co0, uses straight-line depreciation. Cullumber Co. purchased machinery that cost $3600000 on January 4. 2019. The entire cost was recorded as an expense. The machinery has a 9 -year life and a $260000 residual value. The error was discovered on December 20, 2021. Ignore income tax considerations. Before the correction was made, and before the books were closed on December 31, 2021, retained earnings was understated by $3600000. $2857778. $2420000. $2800000