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 , 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
The error in Mike's work occurs in Step 4.
In Step 3, Mike correctly determines that his number of books sold, b, is equal to 22.
However, in Step 4, Mike incorrectly calculates his earnings, m, as 2(22 + 4) = 52.
This is incorrect because according to the given equation, the additional $4 is only earned if the number of books sold is more than 10. Since Mike sold 22 books, he meets this criteria and should have added the additional $4 to his earnings. Therefore, his correct earnings should be $2(22) + $4 = $48.
The correct answer is D. Step 4.