Alistar has an annual income of $25,000. he decides to take classes on line and at night so that he can continue to work. after 3 years he gets his degree and immediately starts earning $32,000 per year. if it takes alistar 6 years to recover his investment for his education, how much did it cost him?

It is not quiet clear whether it takes 6 years after he got his degree to recover his investment or it takes 6 years in total (including 3 years while he was studying).
If it is including 3 years while he was studying we write equation:
3*25000 + 3*32000 = x      where x is the cost of his education.
x = $171 000

In other case the equation looks like:
3*25000 + 6*32000 = x
x = $267000