The answer is D. $9000. Can some please explain. I don't know how to get to the answer and why is it understated

Multiple Choice Question 58 | Your answer is incorrect. Wildhorse Company's December 31 year-end financial statements contained the following errors: Dec. 31, 2017 $40000 understated 11000 understated Dec. 31, 2018 Ending inventory Depreciation expense $56000 overstated An insurance premium of $79500 was prepaid in 2017 covering the years 2017, 2018, and 2019. The prepayment was recorded with a debit to insurance expense. In addition, on December 31, 2018, fully depreciated machinery was sold for $38500 cash, but the sale was not recorded until 2019. There were no other errors during 2018 or 2019 and no corrections have been made for any of the errors. Ignore income tax considerations. What is the total net effect of the errors on the amount of Wildhorse's working capital at December 31, 2018? OWorking capital overstated by $25500 Working capital understated by $53000 Working capital overstated by $13500 Working capital understated by $9000