Ihave no idea how to do any of this

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

Find the difference (8ab+a+2) - (3ab+6)

Human body temperatures have a mean of 98.20° f and a standard deviation of 0.62°. sally's temperature can be described by z = 1.4. what is her temperature? round your answer to the nearest hundredth. 99.07°f 97.33°f 99.60°f 100.45°f