How much does an employee cost?

The case

There was an employee working for a company. He was really good in some activities, but he also got some negative feedback because of few impartial and several biased reasons. At the result, his boss decided not to raise the salary, and after few months that guy left the company.

This event created urgent demand for a new person who can take that position, and the company finally was able to find a candidate "on time":

• As always, new person required some training for that particular position;
• That new person was less qualified than a guy that had left the company, but it was the best choice in terms of cost/qualification;
  
• The company had to pay newcomer higher salary, than the previous employee would be satisfied with...
  

The question

So how much does an employee cost?


The answer

The case almost answers this question itself... Actually, it's even possible to provide exact formula (I think I can), but who really cares?..