Geometry. Very simple question. I have made it worth 25 pints because I am feeling generous

What is the volume of the sphere shown below with a radius of 3?

Simplify a7/a4 a) 1/a3 b)-a/a2 c)a4/a3 d)a3

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?