You can get this simple answer by finding the number value of 3.5%, which would be .035. Since you are trying to go up by 3.5%, you can take the .035 and add a 1 onto it to signify that you are not losing any money, you are gaining it or staying the same at least. If you want to see how much money he will have after 4 years, just multiply 80 by 1.035, then take the answer and multiply it by 1.035 again. Then take the answer and do it again to signify the third year, and then take that answer and multiply it by 1.035 to signify the fourth and final year. You will see that he gets about $91.80 after 4 years.
