Answer:
The correct answer is "C" (Addition property of equality)
Explanation:
1. Are the two expression equal in anyway to each other?
2. When adding a value for example as show in the question "y=3", do both equations still remain equal to one another?
3. When you solve the equation for example as in the equation (change the letter y into a 3), is the answer correct and also equal to the other equation?
If all of these steps are true then your dealing with an Addition Property of Equality(APE).