Answer:
The answer is: $100
Explanation:
John's producer surplus can be determined by subtracting the old tutor salary form the new tutor salary = $400 - $300 = $100
To determine Emily's producer surplus we must first decide if Emily was willing to work or not for the old $300 tutor salary. If Emily was willing to work for a $300 tutor salary, then her producer surplus will equal John's ($100). But personally I believe that Emily started working because the salary increased, so her producer surplus will be $0. The question is not very clear about when Emily decided to start working.
