What was the main idea of the chapter? that the people in rosetto weren't dying of heart disease; instead old age
What supporting details were given? they didn't exercise, ate fattening food, and kept their body in bad condition.
What other ideas were offered? that if you were to actually try, then anyone can change the world
Is this fact or opinion or both?its both because the man ran tests to show that it was factual; but he also gave his opinion 
How do you know? he ran tests to see why the people were dying