So for this you will be using an exponential equation, which is
with a=initial value, b=growth/decay, y = total balance, and x = # of years
In this case, a = 500, and since with this problem the initial value is growing, you will add 100% to 6% to get 106%, or 1.06. The equation will be formed as such: ![y=500(1.06)^x](https://tex.z-dn.net/?f=%20y%3D500%281.06%29%5Ex%20)
With this problem, just plug in 15 into x and solve for y: ![y=500(1.06)^{15}\\ y=1198.28](https://tex.z-dn.net/?f=%20y%3D500%281.06%29%5E%7B15%7D%5C%5C%20y%3D1198.28%20)
In short, after 15 years Tom will have $1198.28 in his account.