Edy,
Navigate to your J2EE server's System Info page via http(s)://<server>:<port>/monitoring/SystemInfo. Note that this path is case-sensitive, so you must capitalize the S and I in SystemInfo. This will bring you to an overview page. Near the top you will see a section titled Software Components, with the SAP-JEECOR and SAP-JEE versions listed. Just to the right is a link for all components. Click that. (Note that you can navigate directly to this next page with the URL //<server>:<port>/monitoring/ComponentInfo).
Now you will see a full list of all the components with their versions. CORE-TOOLS should be just a little way down the list. It will give you the major release and support pack version, and then in parentheses you can determine the hotfix or minor patch level. For instance, you might see 7.01 SP13 (1000.7.01.13.1.20130226064239). This indicates NetWeaver release 7.01, Support Pack 13, Patch Level 1.
Regards,
Matt