Question

1. A website promoting the use of alternative energy vehicles and hybrid technologies claims that, \"A typical automobile in the USA uses about 40 gallons of gasoline every month, producing about 750 lbs of carbon dioxide.\" To determine the truth of this statement, calculate how many pounds of carbon dioxide are produced when 40.00 gallons of gasoline are combusted. Assume that the primary ingredient in gasoline is octane, C8H18(l), which has a density of 0.703 g·mL–1.

I have no idea how to start this problem. The answer is supposed to be in lbs of CO2 but we haven't used anything but the metric system in chemistry. Any help is really appreciated!