Your grandfather put some money in an account for you on the day you were born. You are now $17$ years old and are allowed to withdraw the money for the first time. The account currently has $$$$4$ comma $738$ in it and pays an $7\%$ interest rate.

a$.$ How much money would be in the account if you left the money there until your $20$th $$birthday$?$

b$.$ What if you left the money until your $70$th $$birthday$?$

c$.$ How much money did your grandfather originally put in the$$ account?