Sheffield Company started operations on January 1, 2015, and has used the FIFO method of inventory valuation since its inception. In 2021, it decides to switch to the average-cost method. You are provided with the following information. Retained Earnings Net Income (Ending Balance) Under FIFO Under Average-Cost Under FIFO 2015 $92,900 $82,500 $93,000 2016 66,100 61,000 155,900 2017 94,000 84,900 229,000 2018 119,900 129,900 350,700 2019 296,700 285,700 539,200 2020 294,400 298,900 717,200 (a) What is the beginning retained earnings balance at January 1, 2017, if Sheffield prepares comparative financial statements starting in 2017? Retained earnings, January 1 $ 140400 (b) What is the beginning retained earnings balance at January 1, 2020, if Sheffield prepares comparative financial statements starting in 2020? Retained earnings, January 1 LA $ 493600