Can someone help me?

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

The volume of a sphere is increased by 6%. calculate the corresponding percentage increased in it area.

Anew obstacle course is home to several new types of challenging obstacles. one such obstacle is traversing a 15-stair staircase. to make it more challenging, the stairs are not uniformly spaced. rather, the vertical space between consecutive stairs for the first 10 stairs is 113 feet and the vertical space for the last 5 stairs is 134 feet. what is the total vertical distance traveled ascending and descending the entire 15-stair staircase?