An engineer has a fluctuating future budget for the maintenance of a particular machine. During each of the first years $10,000 per year will be budgeted. During the second 5 years, the annual budget will be $15,000 per year. In addition, $5,000 will be budgeted for an overhaul of the machine at the end of the fourth year, and again at the end of the eighth year. What uniform annual expenditure will be equivalent, if the interest rate is 8% per year?