Ampersand \& Gravel is a construction company. The company's income statement for the 2018 fiscal year included the following information ( $ in millions): The company's balance sheet for 2018 and 2017 included the following information ( $ in millions) The statement of cash flows reported bad debt expense for 2018 of \$3 million. The summary of significant accounting policies included the following notes ( $ in millions): Accounts Receivable (in part) The allowance for uncollectible accounts was $9 and $12 at December 31, 2018 and 2017, respectively. All sales are on credit. Inventories Inventories are valued at the lower of cost or market. The cost of the majority of inventories is measured using the last in, first out (LIFO) method. Other inventories are measured principally at average cost and consist mostly of foreign inventory and certain raw materials. If the entire inventory had been valued on an average cost basis, inventory would have been higher by $460 and $355 at the end of 2018 and 2017 , respectively. During 2018, 2017, and 2016, liquidation of LIFO layers generated income of \$6, \$7, and $25, respectively. Using the information provided: 1. Determine the amount of accounts receivable Ampersand \& Gravel wrote off during 2018. 2. Calculate the amount of cash collected from customers during 2018. 3. Calculate what cost of goods sold would have been for 2018 if the company had used average cost to value its entire inventory. (Hint: prepare a t-account for Inventory at LIFO and then again at Average.) 4. Calculate the following ratios for 2018 (round to two decimal places): a. Receivables turnover ratio b. Inventory turnover ratio c. Gross profit ratio