PLEASE: I already have the answers to question but I just need to understand how did they get $1,700 under Number of Units from first FIFO periodic given!!!! Please explain how to get each Number of units from the cost of goods available for sale for the FIFO periodic!!!!

Instructions Compute cost of goods sold, assuming Ehlo uses: a. Periodic system, FIFO cost flow b. Perpetual system, FIFO cost flow c. Periodic system, LIFO cost flow d. Perpetual system, LIFO cost flow e. Periodic system, weighted-average cost flow f. Perpetual system, moving-average cost flow