Many people like to complain about how expensive mailing a letter has become. They cite, for example, that in 1939, a first-class letter cost only 3 c, whereas in 1996 an equivalent letter costs 32 cents- over ten times more! Find the average annual rate of inflation in 6. ming harges over that 57-ycar period.(5 points). a. 4.24% b. 3.50% c. cannot be determined d. 10.50% three vears ago. At the beginning of