combination of several variables in driver I am looking for a tutorial or example of a blend file showing in the drivers the combination of several variables

thanks
It's really pretty simple. You hit 'Add Variable' several times, pick the sources you want, name the variables in their top most fields more intelligently than me and then use the exact same names in the expression.

In this example, I just add the Y values of the latin gang together and drive Bombo's Y axis with them.

1.055 + 1.138 + 0.906 = 3.099