Brenda is 25 years old today and she wishes to accumulate enough money over the next 35 years to provide for a 20 year retirement annuity of $100,000 at the begining of each year, starting with her 60th birthday. She can save $2,000 at the end of each of the next 10 years and $3,000 each year for the following 10 years. How much must she save each year at the end of years 21 through 35 to obtain her goal? Assume that the average rate of return over the entire period will be 10%. Please show all work.