The following are selected transactions and other data of the Custer Company: Purchased 20 units at $360 per unit on account on 2010 September 18 . Sold 6 units on account for $576 per unit on 2010 September 20. Discovered a shortage of $2,640 at year-end after a physical inventory. Prepare journal entries for these transactions using FIFO perpetual inventory procedure. Assume the beginning inventory consists of 20 units at $336 per unit