Rembrandt framed his masterpiece. The painting by itself is a rectangle with length 20 \text{ cm}20 cm20, start text, space, c, m, end text and width 16 \text{ cm}16 cm16, start text, space, c, m, end text. The painting and frame together form a larger rectangle with length 25 \text{ cm}25 cm25, start text, space, c, m, end text and width 20 \text{ cm}20 cm

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?