I have a basic 'shape' or 'surface' based on a simple formula (i.e., z = x + y).
I have another basic 'shape' or 'surface' based on another simple formula (i.e., z = 2x + y).
I would like a way to superimpose these two 'shapes', 'surfaces', or 'formulae' on top of each other so that they appear in the same 'plot' or 'box'.
How can I accomplish this? I can provide clearer instructions if this is not clear.