I have 2 similar application problems that I can't seem to figure out...

1) A firm buys 12 file cabinets at $140 each, with the bill due in 90 days. How much must the firm deposit now to have enough to pay the bill if money is worth 12% per year? Use 360 days in a year.

and

2) If you want to earn 15% annual simple interest on an investment, how much should you pay for a note that will be worth $13,500 in 10 months?

The answer for #1 (back of the book) is $1,631.07 and the answer for #2 is $12,000.

For question 1, I'm coming up with $1,612.80 by using the formula: I=prt, which comes out to 1680(0.12)(1/3)

For question 2, I am completely clueless as to how to even begin this problem!