Question

The US exports 200 billion pounds of coal. How many tons does the US export?

Answer 1

2,000 = 1 ton .  2,000,000,000/2,000 = 1,000,000,000 or 100 million tons

Answer 2

200 billion is 200,000,000,000 lbs
1 ton is 2,000 lbs.
So 200,000,000,000/2,000 = 100,000,000 tons or 100 million tons.