please solve part (b). mathematically without Excel.

82. You take out a loan to buy a new audio system. Your equal annual payments are 20 percent or ytN borrowed. The interest rate on the loan is 7 1*rcent annually. a. Determine the numtrr of years you will required to make payrncnts (may a non-whole year saxh as 4.791. for example). b. If you make the same payment for an integer number of years. rounding up from your answer in pan what interest rate will you be paying?