New test

Last one was to easy.

I started working at 15. I spent 1/4 of my working life in a factory. I spent 1/5 of my working life in an office, and I spent 1/3 of my working life as a school administrator. For the last 13 years of my working life I have been a stand up comic. How old am I. How did you arrive at the answer, and how do you know it is correct.