Can you please explain and calculate how you got the answers. also how do we figure out the 'Ref'

We have purchased 20 items of inventory at $2,500 each on 26 July 2019 from Suppliers on account. Ignore GST Suppliers is your only creditor. Assume a perpetual inventory system, as per the Practice Set. All numerical answers should consist of digits from 0 to 9 (no symbols, spaces or commas). Dates should be entered as dd/mm/yy (eg 01/06/19). Each box must have an answer - If it would normally be blank enter 0. Select whether the following are impacted by this transaction. Inventory Subsidiary Ledgers Which special journal will this transaction be recorded in? What is the most likely date that this transaction will be posted to: The General Ledger: The Subsidiary Ledger: Enter the transaction into the journal provided, update inventory and post to the subsidiary and general ledger. Purchases Journal (P1) Inventorv Record Accounts Payable Subsidiary Ledger General Ledger Assume you pay the full amount owing to Suppliers on 02/08/19. Complete the journal recording this payment: Journal (CP1)