Sam is paid $50 per room that he paints and he can paint a room in exactly 2
hours. On Sunday, Sam hopes to make at least $150 painting rooms and can
work for exactly 10 hours. Which of the following sets represents the range of
hours (h) that Sam can work without violating either his monetary or time
restriction?

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?