Cheng takes 10 hours longer to pave a driveway than Sammy to do a job. Working together they can do the job in 12 hours. How long does it take each working alone?

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.