DeShawn's Detailing is a service that details cars at the customers' homes or places of work. DeShawn's cost for a basic detailing package is $40, and he charges $75 for this service. For a total price of $90, DeShawn will also detail the car's engine, a service that adds an additional $20 to the total cost of the package. What is the marginal cost of adding the engine detailing to the basic detailing package?
The Marginal cost is the additional cost incurred for the production of an additional unit of output. So being the additional unit the engine, the cost of adding this extra unit is $20, as it says on the question.
