Music, in 2001, full-length cassettes represented 3.4% of total music sales. Between 2001 and 2006, the percent decreased by about 0.5% per year.

a. Write an equation to find the percent P of recorded music sold as full-length cassettes for any year x between 2001 and 2006

b. Find the percent of recorded music sold as full-length cassettes in 2004.