Sally sold 11 books and Mike sold 22 books.
The money they will earn, if they sell more than 10 books, is represented by the equation m=2b+4, where b represents the number of books sold, and m represents the money they will earn.
Mike incorrectly determined that he earned twice as much as Sally. Each step of his work is shown in the table below.
Steps Mike's Work
1 For Sally b = 11
2 For Sally m = 2(11) + 4
3 For Mike b = 22
4 For Mike m = 2(22 + 4)
In which step did Mike make an error?