Delfina deposited $6 200 in her Leftside Bank account which pays simple interest at 2.5% per annum. If she had deposited that money in Rightside Bank for 2 years, she would have earned an interest of $124 more than in Leftside Bank.
a. Find the simple interest rate given by Rightside Bank.
b. How long would she need to invest in Rightside Bank to have $7 285 in the account?