Sally and Mike are both selling books. Each of them will earn $2 per book sold plus an additional $4 if they sell more than 10 books.
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?
A.
Step 1
B.
Step 2
C.
Step 3
D.
Step 4
Mike made an error in Step 4 when he wrote m = 2(22 + 4).
The correct equation for Mike's earnings is m = 2b + 4, where b represents the number of books sold.
In Step 3, Mike correctly determined that b = 22, but in Step 4, he incorrectly wrote m = 2(22 + 4).
The correct equation should be m = 2(22) + 4.
Therefore, the correct answer is D.