please help with questions 18-20 and explain how you did it? Im confused for my exam!!

Use the following information to answer questions 18 to 21: Consider the following data for Reed Com pany for the current year: Total S550 264 260 720 Unit Cost Beginning inventory Purchase February 4 Purchase May 15 Purchase October 20 S10 12 13 15 20 48 Sales during the year, 84 units $30 each 18. What is the cost of ending inventory, assuming the LIFO method is used? A. S889 S905 C. 5622 D. S1,172 19. What is cost of goods sold, assuming the FIFO method is used? A. S889 B. S905 C. $622 D. S1,172 20. What is Reed Company's gross profit percentage (rounded) for the year, assuming that ending inventory totaled $685? a. 56% b. 27% C. 40%