A man wants to help provide a college education for his young daughter. He can afford to invest $800/yr for the next four years, beginning on the girl's fourth birthday. He wishes to give his daughter $5,000 on her 18th, 19th, 20th, and 21st birthdays, for a total of $20,000. Assuming 5% annual interest, what uniform annual investment will he have to make on the girl's 8th through 17th birthdays?