Variables are not the same in computer programming as math. In math you solve for a variable, and in computer programming we assign variables quantities, not solving for them.
When you create a variable, you can affect either one or all of the sprites, and those are the two different scopes.
A variable can store one value at a time.
Neither variable has been or could be assigned a value, so therefor nothing will happen.
What is happening in this code snippet is that they all will end up equaling each other.