The following errors were discovered after the preparation of a trial balance. Which TWO errors would cancel each other out? I. The purchases day book was overcast by ₦2,000 II. A payment of ₦2,000 to a supplier was not posted to the supplier's account III. Discount received of ₦2,000 was debited to discount allowed account IV. A cash sale of ₦2,000 was not recorded in the cash book

Error I (overcast of purchases day book by ₦2,000) inflates the debit side by ₦2,000. Error IV (cash sale of ₦2,000 not recorded in the cash book) omits a debit entry of ₦2,000 from the cash book, reducing the debit side by ₦2,000. These two errors have equal and opposite effects on the debit side and therefore cancel each other out, leaving the trial balance unaffected. The other combinations do not produce equal and opposite effects on the same side.