A company is conducting an audit of its accounts payable to ensure that all payments made to suppliers are accurate. The company has identified two invoices with errors.

Invoice 1 was for $5,000 but the supplier mistakenly charged $5,500.

Invoice 2 was for $7,200 but the company mistakenly paid $7,000.

Calculate the total amount of overpayment or underpayment and express the answer as a percentage of the total amount invoiced.