Solving an equation (or a system) and using the result in further calculations

Nothice that this doesn't actually assign any of these values to x or y:  These are simply a set of rules allowing you to assign these solutions to x and y.

To actually use these solutions, try the following:

This assigns the set of solutions "rules" to the name "systemSolutions"

Now, we can plug ALL of those solutions into an expression in x and y at the same time:

Or, you can get numerical values for these by: