Jason earns S (h, c) = 20h (1 + c/100)1.5 dollars per month at a used car lot, where h is the number of hours worked and c is the number of cars sold. He has already worked 160 hours and sold 69 cars. Right now Jason wants to go home but wonders how much more he might earn if he stays another 10 minutes with a customer who is considering buying a car. Use the Linear Approximation to estimate how much extra money Jason will earn if he sells his 70th car during these 10 min.