Solve the following math problem: In Johnstown, the population is 80 and every single person drives by themselves to work. Each car on a road pollutes 10 pounds of carbon a year. A single bus pollutes 100 pounds of carbon a year. A bus can hold 40 people. The town decides to start running a bus and 25% of the people who used to drive now take the bus. How many fewer pounds of carbon are now emitted per year?