please show the procedure

Dottie's Tax Service specialises in federal tax returns for professional clients such as, Physicians, Dentists, Accountants and Lawyers. A recent audit by the IRS of the returns she prepared indicated that an error was made on 7 percent of the returns she prepared last year. Assuming this rate continues into this year and she prepares 80 returns, what is the probability that she makes errors on: (a) More than six returns? (b) At least six returns? Ea a ) Exactly six returns