Your company works with freelance writers, and Kenji, your colleague, is responsible for processing the freelancers' invoices. Last week, Kenji accidentally input $560 instead of $650 on one of the invoices. The writer hasn't contacted you about the error yet, and you need to e-mail her to let her know that there was a mistake and that she should receive the rest of her payment soon. The following sentence is an excerpt from your e-mail: "Kenji made an error when he was processing your invoice." The sentence excerpted from the e-mail uses voice. Given the purpose of your message, this voice appropriate.