Sandhill 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 Sandhill prepares comparative financial statements starting in 2017? Retained earnings, January 1 (a) What is the beginning retained earnings balance at January 1, 2017, if Sandhill prepares comparative financial statements starting in 2017? Retained earnings, January 1 $ (b) What is the beginning retained earnings balance at January 1.2020, it Sandhill prepares comparative financial statements starting in 2020 ? Retained earnings, January 1 (c) What is the beginning retained earnings balance at January 1, 2021, if Sandhill prepares single-period financial statements for 2021? Retained earnings, January 1$ (d) What is the net income reported by Sandhill in the 2020 income statement if it prepares comparative financial statements starting with 2018