sequences, differentiation , calculus, how to get a sequence

hey guys i was trying to do some questions from my textbook bt i couldn't figure it out

Jo and Ed borrow 200 000 dollars to buy a house. The house is valued at 320 000 dollars.
According to the mortgage agreement they agree to make repayments of 500 dollars per month, until the
house is paid off, or until 25 years passes. The interest charged by the bank on the amount owing is fixed
at 8 percent per year (which they say is equivalent to 0.67 percent per month). Interest is to be charged
at the end of each month, and the 500 dollars repayment is credited after the interest has been charged,
also at the end of each month.
(a) Write a sequence which represents the repayments made.
(b) Write a series which represents the total amount repayed after n months.
(c) Write the first 3 terms of a sequence which represents the amount owing after n months. Include full
working, with written explanations of how your method works.
(d) How long (if ever) will it take for Jo and Ed to pay off their house?
(e) The bank has a policy of enforcing a mortagee sale if the indebitness rises above the house valuation.
Estimate when (if ever) the house will be sold as a mortagee sale.
Hint: the sum of the first n terms in the geometric series a + ar + ar
2 + ... is given by
a(r
n − 1)
r − 1
.
(f ) Imagine Jo and Ed are your friends. They hear you have done maths 208, and come to you for
advice about their mortgage. In simple non-technical language tell them what they should do, giving
enough reasons to convince them that your advice is valid.


if you guys can please help me out

You didn't show any work when (a) and (b) are extremely easy--for (a), the amount repaid after n months is just $500*n. You'll have to show some work representing a serious try at the question before I discuss the remaining parts.