A diner charges $0.80 per egg and $3.00 for three pancakes. Another diner charges $5.00 for three pancakes and $0.30 per egg if a customer orders three pancakes, the two diners charge the same amount for the order if the customer also order how many eggs.

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?