I'm just starting JavaScript and I can't declare a variable. Possible that it is being declared but when I use the variables in a math equation there is no output from that equation.

For example:

JavaScript Variables

In this example, x, y, and z are variables.

I load this .html file into the web browser and the only thing that is output to the web browser is this:

JavaScript Variables

In this example, x, y, and z are variables.