The annual production of carbon dioxide is 124121.49×10^{6}[/tex] kg.
First we calculate the fuel consumed by each car in a year
Fuel consumed=6990/21.4=326.63 gallon
Now we calculate the amount of fuel consumed by 40 million cars in a year
Fuel consumed=326.63*40*10^6=13065.42 million gallon,
Now we can calculate the annual production of carbon dioxide in the USA
CO2 production rate=9.50*13065.42=124121.49*10^6 kg
Therefore the annual production of carbon dioxide in USA is 124121.49×10^{6}[/tex] kg