PLEASE EXPLAIN THIS AND ANSWER ASAP!!

E7-3 (Algo) Inferring Missing Amounts Based on Income Statement Relationships L07-1 Enter the missing dollar amounts for the income statement for each of the following independent cases: Cases Sales Revenue Beginning Inventory Purchases Total Available Ending Inventory Cost of Goods Sold Gross Profit Expenses Pretax Income (Loss) $ $ $ $ 440 $ 180 1,200 1,340 250 160 160 1,000 1,040 160 280 420 250 OTO - 260| 230 120 150 180 8701 1,120 620 990 1,190 450 (100)