If a wrong amount is posted to ledger from the subsidiary book, the effect would be confined to that account only in the ledger. The total of the relevant subsidiary book, posted to ledger, would be correct and will not need rectification.
A credit note for $450 issued to David was recorded correctly in the returns inwards book but posted to the Cr. of his personal account as $480. (It follows that the total of returns inwards book would be correctly posted to the returns inwards account in the ledger whereas David’s personal account is over-credited by $30.)
An invoice for $1,380 issued to John was recorded correctly in the sales book but posted to the Dr. side of his personal account as $1,830. It follows that the total of sales book would be correctly posted to the Sales Account in the ledger whereas john’s personal account would be over-debited by $450.