Nine friends order 4 large pizzas. four of the friends share 2 pizzas equally and the other 5 friends share 2 pizzas equally. in which group does each member get a greater amount of pizza?

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?