Barbara flynn is in charge of maintaining hospital supplies at general hospital. during the past year, the mean lead time demand for bandage bx-5 was 75 (and was normally distributed). furthermore, the standard deviation for bx-5 was 7. ms. flynn would like to maintain a 95% service level. refer to the standard normal table for z-values.

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?