Description: The example of a scale where we try to achieve balance helps to explain why we do the same thing to both sides of an equation. Created by Sal Khan. And my question to you is, what could we do to either side of this scale in order to figure out what the mystery mass is? Is there something that we can do, either removing or adding these things, so that we can figure out what this mystery mass is? Well, to figure out what this mystery mass is, we essentially just want this on one side of this scale.*Teacher Advisor is 100% free.