69. Car Wash Profit The weekly profit, p, in dollars, at Delta
Sonic Car Wash can be estimated by p = 20n – 400,
where n is the number of cars washed in 1 week.
a) Draw a graph of weekly profit versus number of cars
washed for up to and including 100 cars.
b) Use the function to determine the weekly profit if 50
cars are washed.
c) If the weekly profit was $1000, use the function to de-
termine how many cars were washed.