Answer:
Lauer Corporation
The Cost of Goods Sold using the LIFO cost flow assumption is:
$740,000 ($780,000 - $40,000)
Explanation:
Date Transaction             Number of Units    Cost per Unit   Total
1/1      Beginning Inventory     100                   $ 800              $80,000
5/5    Purchase                      200                   $ 900               180,000
8/10   Purchase                      300                 $ 1,000              300,000
10/15 Purchase                      200                  $ 1,100              220,000
Year Total                              800                                          $780,000
Year  Sales                            750                                         $ 740,000
Year  Ending Inventory          50                   $ 800               $40,000 
b) The Cost of goods sold ($740,000) is determined by subtracting the ending inventory ($40,000) from the cost of goods available for sale ($780,000).   Other method of determining the cost of goods sold under the LIFO cost flow assumption would be to add up the individual costs of purchases to the beginning inventory and then subtract ending inventory.  The LIFO cost flow assumption assumes that items sold are from the latest inventory and not the earlier ones.