I am so confused as to how to start on each of these problems. What are the steps for each and where certain numbers come from?

Use the following inventory related information for Questions 119-121 6o On September 1, the beginning inventory for Burkemper Company was 110 units at $100 each. Purchases and sales during September were: Sept7 120 units@ $112 13,440 Sept 12 Sept 17 Sept 25 100 units@$84400 Sept 29 70 units 1, 80 110 units 98 : qG80 90 units81-7S8 7@units @ $88 %4,140 Sept 22 119. What is the cost of ending inventory for Burkemper Company on September 30 if the perlodic LIFO costing method is used? (4 Points) A) $14,320 B) $11,040 $13,240 $13,000 120. What is the cost of goods sold for September for Burkemper Company if the periodic FIFO costing method is used? (4 Points) $27,840 B) $25,760 C) $27,960 D) $27,800 121. What is the cost of ending inventory for September for Burkemper Company if the periodic weighted-average costing method is used? (Round your answer to the nearest dollar) (4 Points) A) $10,932 B) $12,675 $10,726 ) $12,552