Joan quit her job at GM when she was 35 years old. Her friend, who is a financial advisor, recommended that she leave her 401(k) retirement savings in GM's retirement plan rather than withdrawing or transferring the money to a new plan. Her friend said that, on average, Joan could expect a 6% increase per year if she left her money in the plan for many years, based on the past performance of GM's plan. Joan will not be able to add more money to the GM 401(k) account, but can open a new one at her new job. (a) Create a model for the amount of money Joan will have in her 401(k) after any number of years. Use A for the accumulated amount of money, t for the number of years, and P for the amount of money in the plan when she quit, what is called the principal?