yum's algorithm for resolving dependencies

[Andre Robatino]

When installing packages with yum, if there is more than one enabled repository
that can be used to resolve a dependency, how does yum choose which one to use?

I ask because I modified the instructions for installing the 32-bit wrapped
Flash plugin in 64-bit Fedora:

https://fedoraproject.org/wiki/Flash#32_bit_wrapped_version

and want to make sure that a libstdc++ dependency is satisfied by installing the
32-bit libstdc++ from Fedora's repos, and not Adobe Reader from Adobe's repo, as
described here:

http://lists.fedoraproject.org/pipermail/users/2010-May/373309.html

Do the current instructions guarantee that this can't happen, or is it necessary
to make sure the Adobe repo is disabled when running the first yum install
command (the one installing the nspluginwrapper and alsa-plugins-pulseaudio
packages)?