Esentially you need to subtract n, the amount they sell each car for by c, the amount it costs to produce a car, <em>(which should be less because the company has to make money)</em><em> </em>this would give you the total they make a month, P.
Because the amount of cars is constant, 8000, you can always multiply the cost of the car and how much its sold for by 8000. Otherwise, you would have another variable like k, which would be how many cars sold
