If the time frame given is 9 months, then we can find that 9 months is 3/4 of a year. 3/4 x 2% = 0.015. 0.015 x 400 = 6. He would have made 6 dollars in 9 months.
Answer the the second one:
4.5% x 5 (years) = 0.225. 0.225 x 10,000 = 2,250. Since this is a car loan and not a bank interest for example, we add it to the total cost. I'm pretty sure its the third one.
