An individual purchased an $$80,000$ town house with a down payment of $20\%$ and a $30-$year mortgage with monthly payments. Interest is $12\%$ compounded monthly.

a$.$ If the house is sold at the end of five years for $$90,000,$ how much equity does the individual have? $($Equity is the difference between the current market value and the balanced owed on the loan$).$

b$.$ Of the total amount paid on the mortgage, what portion was principal and what portion interest?