20 points for who ever get it right someone who knows what they doing please

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?

What is the length and width of a 84.5 square foot rug? will mark

Matt had 5 library books. he checked out 1 additional book every week without retuening any books. whats the matching equation