clue needed on using results of previous computations

Thanks to Dan Stanger and Richard Fateman for the 'rhs' suggestion. That 
will do the trick, though it seems a bit awkward, which brings me to my 
next question.

I'm curious why this must be done explicitly in Maxima since it makes 
Maxima significantly harder to use for certain purposes than, say, 
Maple, for many types of interactive problem solving. For lack of a 
better word, Maple's "workspace" is more convenient: it is much easier 
to combine the results of earlier computations into subsequent 
computations. In fact, Maple seems to know to do the substitutions 
automatically.

Is there some advantage to Maxima's approach that outweighs the apparent 
inconvenience? Or is the apparent inconvenience really illusory because 
I'm still not quite using Maxima the "right" way?

I am aware that Maxima predates Maple and Maple borrowed syntax from 
Maxima way back. Does Maple's current approach represent subsequent 
evolution in the idea of what represents the best "workspace" approach? 
Is there any movement to incorporate these features into Maxima? Does 
anyone know what I'm talking about? :)

My impression is based on very limited (one month) experience with 
computer algebra systems. I hope this wasn't too vague, if so I could 
clarify a bit.

Rich