After working for a few years Kamiya has saved up some money and decides to invest that money in a
special type of savings account called a "certificate of
deposit" or CD. This account earns interest each year,
which is added to the total amount of money in the
account. Five years after she first invests, Kamiya
checks on her account to see how much money she
has and finds that she has $4,500. She checks the next
year and notices that she has $4,800.
How much money does Kamiya intially invest?
What are the x and y variables in this problem?