18. Your grandfather is 75 years old. He has total savings of 80,000. He expects that he will live for another 10 years, and will like to spend his savings by then. He places his savings into a bank account earning 10 per cent annually. He will draw equal amount each year- the first withdrawal occurring one year from now-in such a way that his account balance becomes zero at the end of 10 years. How much will be his annual withdrawal?