please answer 2-5 showing your work! thank you!

2. If Greg borrows $105 from the bank at 6.9% simple interest, how much interest does Greg owe if he pays the money after 210 days? 3. If you make quarterly payments of $500 into an ordinary annuity earning an annual interest rate of 3.89% compounded quarterly, how much will you have in the account after 4 years? 4. Liz and Bob just had a baby named Isabelle, and they want to save enough money for Isabelle to go to college. Assume that they start making monthly payments when Isabelle is 7 into an ordinary annuity earning 5.96%, and they calculate that they will need $30,700 by the time Isabella turns 18 . How much should they deposit every month so that they reach their goal? For how many years do you need to invest your money into a bank account earning an annual interest rate of 10.83% compounded monthly if you want to triple your investment? (Round your answer using one decimal place)