Problem 8-21 Finding the Bond Maturity

Argos Corp. has 7 percent coupon bonds making annual payments with a YTM of 6.5 percent. The current yield on these bonds is 6.85 percent.

How many years do these bonds have left until they mature? (Do not round intermediate calculations and round your final answer to 2 decimal places. (e.g., 32.16))

Maturity of bond

years

I need to know how to solve it as well. Maybe an excel spreadsheet