Final answer:
Marlon will have $666.69 after 20 years by depositing $300 into an account with a 4.5% interest rate compounded annually.
Step-by-step explanation:
To calculate the amount of money Marlon will have after 20 years, we can use the formula for compound interest: A = P(1 + r/n)^(nt), where A is the final amount, P is the principal amount (initial deposit), r is the interest rate, n is the number of times the interest is compounded per year, and t is the number of years. Given that Marlon deposits $300 with an interest rate of 4.5% compounded annually, we have A = 300(1 + 0.045/1)^(1*20) = $666.69.