Need help! This is due today, please help

What is the range for 31,39,29,34,37,24,36,33,34,28

Afootball is throw by a quarterback to a receiver

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?