To solve for X in this equation, you would subtract both sides by 14 because our goal is to get X on its own. If we write it out, we see that
X + 14 - 14 = 56 - 14
X=42
Because we have a positive 14, a negative 14 will average out to be 0, but what you do to one side, you must do to the other.
If you have any more questions, feel free to ask!