Solve for the unknown number of years in each of the following: (Do not round intermediate calculations and round your final answers to 2 decimal places (e.g., 32.16).)

Present Value------- Years------ Interest Rate------ Future Value

$ 470 -----------------?----------------- 8 % ---------------- $ 987

720 -----------------?----------------- 12 % ---------------- $1,704

17,500 -----------------?----------------- 18%---------------- $ 275,671

20,600 -----------------?----------------- 14%---------------- $ 303827