You ask to find out why he is asking. Maybe your employee said he gets paid $100.00/hr and he wants to find out if this is true. Maybe he wants to give your employee a giant tip if he is getting paid $20.00/hr. Maybe he feels that he is being unfairly billed. Maybe he wants to ask to employee about side work. Maybe he wants to give the employee an unrelated job. Maybe ???.

Part of our job as salespeople is to uncover questions and needs/objections that may be veiled. In this instance, there's no need to get into operating costs and the like until we find out why the client is curious.