For this case we have the following expression: 414x - 812y - 414x Rewriting we have: 414x - 414x - 812y We group similar terms: (414x - 414x) - 812y Adding we have: 0 - 812y - 812y Answer: The sum of a number and its opposite is 0, and the sum of any number and 0 is the number itself.
