Final answer:
The accountant's error of recording an $85 deposit as $58 results in a $27 addition to the book balance on the bank reconciliation to correct the discrepancy.
Step-by-step explanation:
If the company's accountant mistakenly recorded an $85 deposit as $58, the error would affect the book balance. The difference between $85 and $58 is $27, which should have been added to the book balance but was not due to the mistake. Therefore, the error would be shown on the bank reconciliation as a(n) $27 addition to the book balance to correct the underreported deposit.