The price of a small cabin is $$$$35,000.$ The bank requires a$5\%$ down payment. The buyer is offered two mortgage$$ options: $20-$year fixed at $8\mathrm{.}5\%$ or$30-$year fixed at $8\mathrm{.}5\%.$

Calculate the monthly payments and total interest paid for each option.

How much does the buyer save in interest with the$20-$year option?