On Monday, Harper ran 312 kilometers (km). On Tuesday, she ran another 212 km and on Wednesday she ran 412 km. How many kilometers farther did Harper run on Wednesday than on Monday?

Sara goes on a slingshot ride in an amusement park. she is strapped into a spherical ball that has a radius 3*10^2 of centimeters. what is the volume of air in the spherical ball? use this formula: volume of a sphere=4/3pi,r^3 , where r is the sphere’s radius.