If you invest $100 each month into an account earning 4.5% compounded monthly, how long will it take the account to grow to $20,000

Robert has 78 tomato lants and 56 cucumber plants .he wants to plant them in rows that only have one type of plant in each row with the same number of plants in each row. how many plants should he put in each row and how many rows of each type of plant will he need