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