When a transaction is recorded in the subsidiary book, it is posted to the ledger by posting individual entries to the personal accounts and the total to the relevant nominal account.
If the total of the subsidiary book is posted to the ledger but one or more of the individual entries are not posted from the subsidiary book to the ledger, the trial balance will not agree because total debits will not equal total credits.
A credit note for $2,160, received from Melbourne Wholesalers, was recorded in the returns outwards book but not posted to the company’s personal account in the ledger.
It follows that the Melbourne Wholesalers Account needs to be debited by $2,160 to place the entry in that account. The corresponding credit will be placed in the suspense account.