how extract value from list?



Hi all!
I have a simple question regarding "solve".
Using solve results in a list e.g. [x=a,x=b].
How can I assign the results to a variable, i.e.
I want to do someting like,

x: solve(expr,x);

and then use x in further calculations.

I cannot figure this out, please help me.

Regards,
Johan