Can someone help me with this

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

According to modern science, earth is about 4.5 billion years old and written human history extends back about 10,000 years. suppose the entire history of earth is represented with a 10-meter-long timeline, with the birth of earth on one end and today at the other end.

Asurvey of 2,000 doctors showed that an average of 3 out of 5 doctors use brand x aspirin.how many doctors use brand x aspirin