9514 1404 393
Answer:
(c) addition property of equality
Explanation:
Each side of the equation after the first step is 2 more than it was before the first step. The first step consisted of adding 2 to both sides of the equation.
The "addition property of equality" tells you that the value of the variable remains unchanged if you add the same thing to both sides of the equation. That is, the addition property of equality justifies the fist step of adding 2 to both sides of the equation.