Saundra room is 15 ft long by 9 feet wide. She is putting carpet in the room and cost $3.75 per square foot how many how much will it cost to put carpet in Sandra's room

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?