If you're finding the future value: P=35,000(1-.1/1)^1. this is assuming you want to know the value of it after one year. if you want it to be more years, like two : P=35,000(1-.1/2)^2. When entered into the calculator enter it like so : 35,000(1-(.1/1))^1. when that's done you end up with $31,500. that's the machine's worth. it lost 3,500. 35,000-31500.