This has something to do with geometric series but I'm not sure how to do it.

answer for (a) $13586.80

(b) $35868; $17169.80

I need the solution to these answers.

A person borrows $100 000 at the beginning of a year and agrees to repay the loan in ten equal instalments at the end of each year. Interest is charged at a rate of 6% com- pounded annually, (a) Find the annual repayment. (b) Work out the total amount of interest paid and compare this with the total interest paid when repaying the loan in five equal annual instalments instead of ten