Which of the following errors would cause a trial balance to have unequal totals?

Explain your answers.

a. A payment to a creditor was recorded as a debit to Accounts Payable for $86 and as a credit to Cash for $68.

b. A payment of $100 to a creditor for an account payable was debited to Accounts Receivable and credited to Cash.

c. A purchase of office supplies of $280 was recorded as a debit to Office Supplies for $28 and as a credit to Cash for $28.

d. A purchase of equipment for $300 was recorded as a debit to Supplies for $300 and as a credit to Cash for $300.