How do I run a report on average age of employees?

Summary:

I need to run a quick report on the average age of employees in the whole organisation and per Legal Employer.

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I have the report with employee name, entity and Person Date of Birth. However wondering if there is a quick/simple way to add the Average Age of all employees in the organisation and per location/entity? I am not familiar with adding formulas but happy to try if this is simple and easy? Please help.

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