$13.$Mr Jones has a goal to reach $1,500,000$ in his retirement account in $30$ years. He currently has $$25,000$ in his account. He expects to earn $6\%$ compounded annually in his investments. How much more money must Mr Jones deposit in his account at the end of each month in order to reach his goals?

$14.$Tammy realizes that she has charged too much on her credit card and has racked up $$30,000$ in debt. If Tammy can pay $$600$ each month and the card charges $23$ percent APR $($compounded monthly$),$ how long will it take her to pay off the debt?

$15.$ Given the same information in question #$14,$ how much interest will Tammy pay if she chooses to continue in making monthly payments of $$600?$