how would i obtain this answer? Rate = 8.25%/12 ======> 0.007083333

For context:

Around Town Movers recently purchased a new trucck costing 97,000. The firm financed this purchase at 8.25 percent interest with monthly payments of 2,379.45. How many years will it take the firm to pay off its debt?

A similar question is this:

For context, this is for "Augusta Acres is planning a major expansion 3 years from today. Company sets aside 30,000 each quarter for next three years. How much will firm have when it is ready to expand if it can earn an average of 7.5 percent on its earnings?

I don't know how time manipulates the interest rate...

Full detailed answers to the first question, and the following questions, would be well appreciated. I have been on this for literally 12 hours (among other questions) and I really need allllllllll the help I can get.