4-85 Mark Johnson invests a fixed percentage of his salary at the end of each year. This year he invested $1500 For the next 5 years, he expects his salary to increase 8% annually, and he plans to increase his savings at the same rate. How much will the investments be worth at the end of 6 years if the average increase in the stock market is (a) 8%? (b) 5%? (c) 3%