Sure, here are the simplified steps for upgrading an Oracle Real Application Clusters (RAC) environment:

1. **Backup:** Before starting the upgrade process, ensure you have a complete backup of your Oracle RAC database and configuration.

2. **Pre-Upgrade Tasks:**

   - Review Oracle's documentation for the version you are upgrading to, and ensure your environment meets the prerequisites.

   - Check for any pre-upgrade scripts or tasks recommended by Oracle.

   - Stop all database instances on the cluster.

3. **Software Installation:**

   - Download and install the new Oracle RAC software on all nodes in the cluster.

   - Run the installer and follow the prompts for upgrading the software.

4. **Upgrade the Database:**

   - Start the Oracle Database Upgrade Assistant (DBUA) or perform a manual upgrade using scripts, as per your preference.

   - Follow the steps provided by Oracle for upgrading the database to the new version.

5. **Post-Upgrade Tasks:**

   - Run any post-upgrade scripts recommended by Oracle.

   - Verify the integrity of the upgraded database by performing tests and checks.

   - Update any client configurations or applications that connect to the Oracle RAC database to ensure compatibility with the new version.

6. **Testing and Validation:**

   - Conduct thorough testing of your Oracle RAC environment to ensure all features and functionalities are working as expected.

   - Perform performance testing to validate the upgraded system's performance.

7. **Documentation and Training:**

   - Update documentation, including system configurations, procedures, and any changes made during the upgrade process.

   - Train relevant personnel on any new features or changes introduced in the upgraded Oracle RAC environment.

During an interview, you can elaborate on each step based on your experience and the specifics of the Oracle RAC environment you've worked with.