Heatwave Gaming develops, markets, and publishes electronic games. ZipTrain is one of the largest railway networks in the nation, with over 27,000 miles of railroads. The following data were taken from each of the companies' December 31, 2017, annual reports. Revealing which data relate to which company was intentionally omitted. The dollar amounts are in millions. Sales Depreciation costs Net earnings Current assets Company 1 $ 8,390 840 Company 2 $1,904,900 57,060 300 96,323 Property, plant, and equipment Total assets 3,166 19,960 1,282,125 339,692 24,863 2,535,664 Required a. Calculate depreciation costs as a percentage of sales for each company. (Round your percentage answers to 2 decimal places (i.e., 0.0123 is entered as 1.23%).) b. Calculate property, plant, and equipment as a percentage of total assets for each company. (Round your percentage answers to 2 decimal places (i.e., 0.0123 is entered as 1.23%) .) c. Based on the information now available to you, which company is Ziptrain? d. Which company appears to be using its assets most efficiently?