AutoZone, Inc. uses the perpetual system of inventory and the net method for purchase and sales discounts. 1) On 3/15/19, AutoZone purchases $5,000 (gross) of inventory on account. The invoice is dated 3/15/19 with terms 2/10, n/30. 2) On 3/20/19, AutoZone returns $1,000 (gross) of worth of inventory. 3) On 3/24/19, AutoZone pays the invoice associated with the 3/15/19 purchase.