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Sage 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. (a) What is the beginning retained earnings balance at January 1.2017, if Sage prepares comparative financial statements starting in 2017 ? Retained earnings, January 1 $ (b) What is the beginning retained earnings balance at January 1,2020, if Sage prepares comparative financial statements starting in 2020 ? Retained earnings, January 1 \$s (c) What is the beginning retained carnings balance at January 1, 2021, if Sage prepares single-period financial statements for 2021 ? Retainedearnings January 1 Is (d) What is the net income reported by Sage in the 2020 income statement if it prepares comparative financial statements starting with 2018