
Lenny D. answered 07/18/19
Former Tufts Economics Professor and Wall Street Economist
Producer Surplus is simply the difference Between what you are getting for your output and the minimum amount required to get you to do the same thing. In this case, 50,000 - 30,000 is Joe's Producer surplus. This is also sometimes called an economic rent.
If you have any questions in economics please don't hesitate to reach out. I taught economics at Tufts University
Best,
Lenny D.