Not really sure tbh but I’m going to say the interest rate is 20% I’m sorry if this is wrong but if you subtract 4,000 by 3,200 you get 800 so you’re trying to figure out what percentage it takes from the 4000 it get to 3,200 so i multiplied 0.2 (20%) by 4000 and got 800 which to me makes sense lol so