unmet dependecy; mesa-glx.

libgl1-mesa-glx is a dummy package, that existed only in Ubuntu releases up to jammy (mesa versions up to 22.*).
It seems that you need a newer version of packettracer without that dependency.

For diagnostic purposes please provide the output that you receive for the following commands (to be executed in a terminal window):

uname -a
lsb_relase -crid
apt policy packettracer libgl1-mesa-glx

pkg: dependency problems prevent configuration of packettracer:
 packettracer depends on libgl1-mesa-glx; however:
  Package libgl1-mesa-glx is not installed.
 packettracer depends on libxcb-xinerama0-dev; however:
  Package libxcb-xinerama0-dev is not installed.

dpkg: error processing package packettracer (--install):
 dependency problems - leaving unconfigured
Processing triggers for shared-mime-info (2.4-4) ...
Errors were encountered while processing:
 packettracer

$ uname -a
Linux T16 6.8.0-49-generic #49-Ubuntu SMP PREEMPT_DYNAMIC Mon Nov 4 02:06:24 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

$ lsb_release -crid
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 24.04.1 LTS
Release: 24.04
Codename: noble

$ apt policy packettracer libgl1-mesa-glx
packettracer:
  Installed: (none)
  Candidate: (none)
  Version table:
     8.2.2 -1
        100 /var/lib/dpkg/status
libgl1-mesa-glx:
  Installed: (none)
  Candidate: (none)
  Version table:

Packettracer is a package from a foreign source and apparently there is an obsolete dependency defined in that package that cannot be met on Ubuntu noble.

Repeating from above: libgl1-mesa-glx is an obsolete dummy package, and defining it as a dependency does not make any sense any more.

There is nothing that Ubuntu can do. The solution has to come from outside.
If you search the web for this issue, you will find
https://community.cisco.com/t5/cisco-software-discussions/unable-to-install-packet-tracer-on-ubuntu-24-04-lts/td-p/5079326