A long-term debt issue in the amount of $200 million calls for mandatory redemption payments of $30 million each at the end of years 7, 8, and 9 and

A long-term debt issue in the amount of $200 million calls for mandatory redemption payments of $30 million each at the end of years 7, 8, and 9 and repayment of the remaining balance (called the balloon) at the end of year 10. Calculate the issue's average life.