Can Someone explain to me how the 18 came out? Please

Homework: Chapter 6 Homework Part 7 of 7 Points: 0.92 of 1 Boston Cycles started October with 12 bicycles that cost $42 each. On October 16, Boston purchased 40 bicycles at $68 each. On October 31, Boston sold 34 bicycles for $100 each. Requirements 1. Prepare Boston Cycle's perpetual inventory record assuming the company uses the weighted-average inventory costing method. 2. Journalize the October 16 purchase of merchandise inventory on account and the October 31 sale of merchandise inventory on account. Requirement 1. Prepare Boston Cycle's perpetual inventory record assuming the company uses the weighted average inventory costing method. Start by entering the beginning inventory balances. Enter the transactions in chronological order, calculating new inventory on hand balances after each transaction. Once all of the transactions have been entered into the perpetual record, calculate end of the period. (Abbreviation used: QTY = Quantity: Tot. = Total) Boston Cycles Purchases Cost of Goods Sold Date QTY Unit Cost Tot. Cost QTY Unit Cost Tot. Cost Inventory on Hand QTY Unit Cost Tot. Cost 12 $ 42 $ 504 52 $ 62 $ 3,224 Oct. 1 Oct. 16 40 $ 68 $ 2,720 Oct. 31 34 $ 62 $ 2,108 18$ 62 $ 1.116 $ 2,720 $ $ 2.108 Totals 40 34 1.116 18 Requirement 2. Journalize the October 16 purchase of merchandise inventory on account and the October 31 sale of merchandise inventory on account. (Record debits first, then credits. Select the explanation on the last line of the journal entry tab October 16: Purchased merchandise inventory on account. Date Accounts and Explanation Debit Credit Oct. 16 Merchandise Inventory 2,720 Accounts Payable 2,720 To purchase inventory on account October 31. Sale of merchandise inventory on account