In this tutorial we learn how to use inductive reasoning. Start out with your equation that is giving you your statement. You need to prove whether this is true or not by figuring out the equation. Look at the different angles to see if they are a linear pair and then see if they are the same. Compare them to see if they add up to 180 degrees and use your mathematical logic. Once you understand the backbone to doing this type of math and what the exceptions are, then you will be able to figure it out. If something is true, it must be true all the time.