Each year caronline deposited a certain amount of money in an account which pays an annual interest rate of r so that at the end of each year, the balance in the account is multiplied by a growth factor of x=1+r. $600 is deposited at the start of the first year, and $200 at the start of the following year. Write an expression for a value of the account at the end of three years in terms of growth factors x. Find the value at the end of 3 years if the interest rate is 4%.