A car that averages 22 miles per gallon emits 4.3 metric tons of carbon dioxide per year. A passenger bus emits 9.2 metric tons of carbon dioxide per year and can carry 30 people at a time. How much less carbon dioxide does a commuter who takes a bus emit in a year compared to a commuter who drives everyday?
13.5 metric tons
2.1 metric tons
5.1 metric tons
3.99 metric tons