Question

A student is asked to solve the equation below and to justify her/his steps. Identify what, if anything, is incorrect in her/his math or justification.
x + 4 = –8

Step
Justification
x + 4 = –8
Given
x + 4 + (–4) = –8 + (–4)
Addition property of equality
x = –4


A. The student mislabeled the work in the step 2 as "Addition property of equality."
B. The student improperly applied the "Addition property of equality" in step 2.
C. The student added improperly and got the wrong answer in step 3.
D. There is no error. The student's justification is correct.

Answer 1

This should be the correct solution

x + 4 = -8
x + 4 + (-4) = -8 + (-4)
x + 0 = -12
x = -12

C. The student added improperly and got the wrong answer in step 3.

The student failed to consider the negative signs of 8 and 4.